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Volume 56, 1926
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Australasian Patelloididae.

[Read before the Wellington Philosophical Society, 24th September, 1924; received by Editor, 31st December, 1924; issued separately, 26th April, 1926]

Plate 99.

The classification of the Patelloididae presents such difficulties that few attempts have been made to ascertain the relationships of the many species that have been described under Eschscholtz's genus Acmaea, which includes the bulk of the family. The other genera included in the family, Scurria and Lottia, are American, and do not call for further notice here. A number of genera have been from time to time proposed for the species of this family, but not for the purpose of breaking up the Acmaea group, except, so far as I am aware, in two instances. Dall, in Amer. Journ. Conch., vol. 6, 1871, founded the subgenera Collisella and Collisellina on characters of the radula; and Iredale, in Trans. N.Z. Inst., vol. 47, 1915, proposed Atalacmea, Radiacmea, Parvacmea, and Notoacmea for New Zealand species, mainly on shell characters. It is not the purpose of this paper to discuss the classification of the family, but merely to put on record some observations on the New Zealand and Australian species. A few preliminary remarks of a general nature only, mainly on the characters of the shell and radula, will therefore be offered.

The shells of Patelloididae vary from large limpet-like shells to minute thin and hyaline shells. The shell of Lottia is in texture very similar to that of Cellana. The ribbing, inner surface, and colouring are comparable. Patelloida alticostata, on the other hand, has a shell with high ridges and a white porcellaneous interior recalling that of Scutellastra. The larger species of Notoacmea, which are also the most variable—namely, pileopsis and septiformis—have the young shells thin. They increase in thickness with age but retain the glassy interior. Finally, Notoacmea daedala and Atalacmea fragilis have extremely thin, hyaline, and translucent shells.

Each row of teeth in the radula of the Patelloididae is usually composed of an anterior element of two teeth close together in the middle line, a posterior element of four or more teeth not meeting in the middle line, and, in three genera, one or two marginals. The two anterior teeth I have interpreted as centrals, comparing them with those so named in the Patellidae. They are functional in all species. The four teeth of the posterior element are classified as laterals. Of these the inner ones only appear to be functional in all the genera except Tectura and Radiacmea, in which all the teeth appear to be functional. Marginals, present in Patelloida, Chiazaemea, Asteracmea, and Collisella, are small, and therefore probably not functional. I have adopted a simple formula as sufficiently showing the nature of the teeth. A median central tooth would be indicated by an odd number of centrals, but none occurs in the Patelloididae. It occurs in certain of the Patellidae, where, however, it is functionless. There is a considerable amount of difference between broad teeth with wide recurved cusps, as in Patelloida, and the long curved subulate teeth of Notoacmea. The characters of the radula have been used in defining the genera and subgenera.

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Apparently the shell and radula characters do not always run parallel. By this I mean that species whose shells are alike have quite different teeth, while, conversely, the same radula formula is found in species having very unlike shells. Thus the shells of Tectura testudinalis from British seas agree very closely with those of Notoacmea septiformis from Tasmania, but the teeth, while agreeing in number, differ in arrangement and character. Conversely, while the shells of Collisella spectrum from California and Patelloida alticostata from Australia may be compared, Collisella possesses but one marginal tooth on each side while Patelloida has two. Again, Dall has grouped in the one genus Collisella, on account of agreement in a radula formula 1.2.2.2.1, Collisella spectrum, and C. asmi. But shells with more different texture and shape could scarcely be found in the family.

By treating the principal shell and radula characters as of equal value, eleven definable groups, besides Scurria and Lottia, may be made out. These, so far as they affect the Australasian species, will be treated as distinct genera in the account which follows. In America generally, and in north temperate seas, there is a group typified by Collisella pelta with thick, ribbed, porcellaneous shells, and the teeth of the radula 1.2.2.2.1. Dall's genus Collisella includes these, as well as others with the same radular formula but quite different shells, as asmi. A second northern group is that which includes testudinalis, and is characterized by thin, smooth, sometimes almost translucent shells, and with the teeth of the radula 0.2.2.2.0. To this group the name Tectura should be applied. A third group might be defined as including thin smooth shells with animals having the teeth of the radula 1.2.2.2.1. This would include such species as asmi, paleacea, strigatella, and suchlike.

In the Indo-Pacific region eight groups may be defined in a similar way. Three—Patelloida, Chiazacmea, and Asteracmea—have the radular formula 2.2.2.2.2; whilst five—Radiacmea, Potomacmaea, Actinoleuca, Notoacmea, and Atalacmea—have no marginals, the formula being 0.2.2.2.0. The genera are defined on the characters of the teeth and the shell.

It will appear from the foregoing synopsis that the geographical area occupied by the Patelloididae may be divided into two great regions. One is the western coast of America, with, extensions round Cape Horn, through the Panama to the West Indies, across the Pacific to Japan, and, possibly, by the Arctic Sea to the North Atlantic. This region is characterized by the presence of Collisella, Tectura, Scurria, and Lottia. The other region is the Indo-Pacific, characterized by Patelloida, Asteracmea, Notoacmea, Atalacmea, Actinoleuca, and Radiacmea. The two faunas mingle only in the Malayan region—at least, as far as can be judged on the available information. The two areas where species are most extensively developed are the west coast of North America, and the south coast of Australia, with Tasmania and New Zealand.

In the genera having most teeth in the radula generally only the two centrals and the two inner laterals are functional. From this fact I infer that a large number of teeth is a more archaic character than a small number.

Scurria, which possesses a branchial cordon as well as a plume, and has also functionless marginal and outer laterals, is probably an archaic form. Patelloida and Asteracmea, with the highest number of teeth, are well developed along the south coast of Australia. This region, with Tasmania and New Zealand, is also the headquarters of four genera without marginal teeth. All these circumstances point to a great development of forms in the Southern Hemisphere. On the other hand, Collisella

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perhaps dispersed from the North Pacific. The family as a whole is mainly circum-Pacific in distribution, and may have originated somewhere on the borders of that ocean, but as it is no doubt of very ancient date, Cambrian and Silurian fossils having been referred to it, it is scarcely profitable to speculate further.

If I am right in supposing that the evolution of species in this family has been in the direction of the reduction of teeth in the radula and the development of thin shells as in Tectura and Notoacmea, also the loss of a branchial cordon as the plume took its place, then it might be inferred that the family Patelloididae is an offshoot of Patellidae. The shells of Lottia and Patelloida, archaic genera in the above sense, resemble those of Cellana and Scutellastra respectively.

The following key indicates the relationship of those genera of Patelloididae that have so far been described. Scurria, Lottia, Collisella, Tectura, and Potamacmaea are extra-Australasian genera.

[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]

I. Branchial cordon and plume present.
A.  Branchial cordon complete Scurria.
B.  Branchial cordon interrupted in front Lottia.
II. Branchial plume only present (but see Asteracmea, p. 563).
A.  Radula with 2 marginal teeth on each side.
1. Shell porcellaneous, strongly radiately ribbed Patelloida.
2. Shell smooth, or with small low ribs Chiazacmea.
3. Shell minute, translucent, smooth, or finely radiately striated or ribbed Asteracmea.
B. Radula with 1 marginal tooth on each side Collisella.
C. No marginal teeth; central and lateral teeth diverging in two rows from median line.
a. Teeth with short rounded cusps.
1. Shell porcellaneous, radiately ribbed Radiacmea.
2. Shell thin, hyaline, smooth Tectura.
b. Teeth broad and straight with saw edges Potamacmaea.
c. Teeth broad with straight edges in two diverging lines Naccula.
D. No marginal teeth; central teeth in advance of lateral, which are in a transverse row.
1. Shell conical, porcellaneous, finely ribbed Actinoleuca.
2. Shell with apex usually anterior, with an inner hyaline and an outer shelly often dark-coloured layer Notoacmea.
3. Shell much depressed, hyaline Atalacmea.

Genus Patelloida Quoy and Gaimard.

The shells of this group are thick, porcellaneous in texture, with radiating ridges having a tendency to develop seven larger than the others. The colour inside is either entirely white or with colour at the margin and on the spatula which is often spotted with lighter. P. latistrigata is the darkest-coloured species, being some shade of brown both within and without.

The radula bears 2 anterior centrals with broad recurved cusps; 2 laterals posterior to these on each side, the inner with broad recurved cusps, the outer small; and 2 small marginals on each side. Only the centrals and 2 inner laterals appear to be functional.

The genus comprises about 6 species, distributed over Malaya, western Polynesia, Australia, Tasmania, and New Zealand. They are mostly found on seaweed-covered rocks about low-tide mark, where they are quite common, but they occur also higher up in the intertidal belt. P. alticostata, with a length of 57 mm., appears to be the largest species.

Patelloida may on conchological characters be divided into two subgeneric groups, Patelloida and Collisellina.

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Subgenus Patelloida Q. & G.

Patelloida Quoy and Gaimard, Voy. “Astrolabe,” Zool., vol. 3, 1834, p. 349. Type: P. rugosa Q. & G.

Shell with regular prominent ribs. Colour predominantly white, the spatula and interior margin dark.

Patelloida (Patelloida) rugosa Q. & G.

Patelloida rugosa Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 366, pl. 71, f. 36, 37, 1834. Amboyna (type in Mus. Hist. Nat., Paris). Acmaea rugosa (Q. & G.): Pilsbry, Man. Conch., vol. 13, p. 52, pl. 37, f. 5, 6, 1891.

I have not seen this species, and can find no information concerning it beyond the original description. This is translated by Pilsbry, and Quoy and Gaimard's figures are reproduced. It is recorded from Amboyna only.

Gray designated this species as type of Patelloida. Iredale states that it is referable to the group including saccharina, while Pilsbry suggests a comparison with P. corticata. It is desirable that the dentition of this species be described.

Patelloida (Patelloida) nigrosulcata (Reeve).

Patella nigrosulcata Reeve, Conch. Icon., vol. 8, pl. 30, f. 84, 1855 (type in British Museum). Patella stellaeformis Reeve var. nigrosulcata Reeve: Pilsbry, Man. Conch., vol. 13, p. 100, pl. 61, f. 66, 67, 1891. Acmaea patellavecta Verco, Trans. Roy. Soc. S. Aust., vol. 36, p. 195, pl. 15, f. 5–7; pl. 16, f. 5, 1912 (Cape Naturaliste). Patelloida patellavecta (Verco): Hedley, Journ. Roy. Soc. W. Aust., vol. 1, p. 35, 1916. Patelloida nigrosulcata (Reeve): Hedley, Proc Linn. Soc. N.S. W., vol. 41, p. 708, 1917.

This species is characterized by about 40 low rounded ribs, margin slightly crenulated, interior white with grey and brown border, exterior white and eroded.

The dentition is distinctive. The centials are broad and short, also the laterals, of which the outer are the broader. As is usual in the genus, the marginals are small.

According to Verco, from whose article the information here given is taken, this species is related to P. alticostata.

Bionomics.—Living on the shell of Patella neglecta, nearly every example of which above 25 mm. in length carries one or more.

Distribution.—Western Australia: Cape Naturaliste, King George Sound, Ellensbrook, Yallingup.

Patelloida (Patelloida) alticostata (Angas).

Description.—Shell characterized by its usually high conical shape and high equidistant and nearly even-sized ribs; the normal number for young shells seems to be 14, increasing with age to about 28. Shell: inside white with spatula dark brown or black at front and round posterior border; margin yellowish with black patches in interspaces between ribs; dark rays often faintly seen through inner layer of shell.

Radula has centrals approximating with broad blunt recurved cusps showing a slight groove most marked on inner face; inner laterals short, with very broad blunt recurved cusps, upper surface of curved portion concave, outer laterals minute; marginals, 2 on each side, transparent; centrals and lateral cusp brown colour with dark-brown tips. (Specimens from Corny Point, South Australia.)

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Good accounts of this species are given by Verco (Trans. Roy. Soc. S. Aust., vol. 30, p. 209, 1906) and Tenison-Woods (Proc. Roy. Soc. Tas., 1876, p. 50, 1877).

This species is fairly uniform throughout its range. Two subspecies are here accepted, based on characters of sculpture, colour, and size, all somewhat variable.

Bionomics.—Intertidal from about half-tide mark down.

Distribution.—Tasmania: and from Geraldton, Western Australia, round the south coast to South Queensland.

(a.)

Subspecies alticostata (Angas).

Patella alticostata Angas, Proc. Zool. Soc., 1865, p. 56 (Port Lincoln, S. Aust.). Acmaea costata (not Sowerby): Tenison-Woods, Proc. Roy. Soc. Tas., 1876, p. 50, 1877: Pilsbry, Man. Conch., vol. 13, p. 51, 1891: Pritchard and Gatliff, Proc. Roy. Soc. Vic., vol. 21, p. 382, 1908. Acmaea alticostata (Angas): Hedley, Proc. Linn. Soc. N.S. W., vol. 29, p. 189, 1904: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 209, 1906; vol. 36, pp. 183, 197, pl. 16, f. 3, 4 (radula), 1912: Iredale, Proc. Zool. Soc., 1914, p. 670. Patelloida alticostata (Angas): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916.

Distinguished by the following characters: Shell depressed or elevated, large, up to 57 mm. long, ribs high and rounded. Interior white, spatula black in front and behind, margin narrowly black and yellow banded.

Distribution.—Tasmania; and the west and south coasts of Australia from Geraldton to Bass Strait.

(b.)

Subspecies antelia Iredale.

Patella costata (not Sowerby *): Angas, Proc. Zool. Soc., 1867, p. 221. Patelloida alticostata Angas, subspp. antelia and complanata Iredale, Proc. Linn. Soc N.S.W., vol. 49, p. 234, 1924 (Sydney).

This subspecies differs from the subspecies alticostata only in characters which are somewhat variable, so that the two subspecies intergrade; but the distinction is convenient, as the geographical range of each is different though conterminous. Iredale divides the present form into two, but I scarcely think such a course is justified. Possibly there may be variations due to differences of exposure. It may be defined as follows:—

Shell usually elevated, small, under 30 mm. long, ribs low, angled. Interior whitish, much stained with black, spatula black in front and behind, margin black-and-yellow banded or with a broad black band.

Bionomics.—At Long Reef, New South Wales, it occurs in the barnacle association in the mid-tide belt, and in the tunicate association in the low-tide belt.

Distribution.—Coasts of eastern Victoria, New South Wales, and South Queensland.

Patelloida (Patelloida) corticate.

Apparently a highly plastic species, the distinguishing characters of which are the thick shells, with the apex forward and usually low; ribs irregular, margin crenulate. Young shells sometimes show seven ribs more prominent than the rest. Inside coloration very various.

[Footnote] * The erroneous application of Sowerby's name Lottia costata to the present species has on several occasions been suggested, but only recently has it been disposed of satisfactorily. Tomhn (Proc. Mal. Soc, vol. 16, p. 98, 1924) identifies it with Patella longicosta Lam.

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The nearest relative of this species is Patelloida alticostata of Australia, from which it differs in its depressed form, irregular ribbing, and coloration.

Dentition 2.2.2.2.2; centrals and laterals broad with recurved cusps; outer laterals of moderate size and apparently functional; dentition essentially like that of P. saccharina.

Three forms, not very well defined, may perhaps be recognized. They will be described separately, and, for the sake of uniformity, called subspecies. They are, however, not of the same value as the subspecies Patelloida flammea and P. latistrigata; they might be described as environmental forms.

Distribution.—Sunday Island (Kermadec Group); throughout New Zealand from the North Cape to Stewart Island; Chatham Island.

(a.)

Subspecies corticata (Hutton).

Acmaea corticata Hutton, Man. N.Z. Moll., p. 89, 1880 (Dunedin: type in Canterbury Museum); Trans. N.Z. Inst., vol. 15, p. 127, pl. 15, f. L (dentition), 1883; Proc. Linn. Soc. N.S. W., vol. 9, p. 372, 1884. Acmaea lacunosa (not Reeve): Pilsbry, Man. Conch., vol. 13, pp. 52, 168, pl. 37, f. 9–11, 1891. Acmaea stella subsp. corticata Hutton: Suter, Proc. Mal. Soc., vol. 7, p. 325, pl. 27, f. 38–41, 1907; Man. N.Z. Moll., p. 74, pl. 5, f. 17, 1913: Bucknill, Sea-shells N.Z., p. 14, pl. 5, f. 2, 1924.

In this form there are 25–30 fairly even-sized ribs; apex high and about the anterior third. Inside bluish-white with radiating bands of brown sometimes more or less obscured by the nacreous layer.

It varies somewhat, passing into the next subspecies, from which it may be distinguished by the higher form, more numerous ribs, and regular colour-bands; it is also smaller, 14 mm. being the usual length of the adult.

Bionomics.—Found on rocks between tide-marks, often in very exposed situations, such as rock-faces in the surf zone, where it is common. It is invariably covered with Melobesia, which also covers the rock-surface on which it lives. It is a member of the large-brown-algae associations and the Modiolus pulex association at St. Clair.

Distribution.—Te Henga, Banks Peninsula, Shag Point, Otago Peninsula, Stewart Island, Chatham Island (Suter).

(b.)

Subspecies corallina n. subsp.

Acmaea stella (not Lesson): Suter, Proc. Mal. Soc., vol. 7, p. 324, pl. 27, f. 36, 37, 1907; Man. N.Z. Moll., p. 73, pl. 5, f. 16, 1913: Iredale, Proc. Zool. Soc., 1914, p. 671: Bucknill, Sea-shells N.Z., p. 14, pl. 5, f. 1, 1924. Patelloida stella (not Lesson): Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924. Acmaea lacunosa (not Reeve): Hutton, Macleay Mem. Vol., p. 72, 1893.

Distinguished from corticata by its large size, depressed form, fewer ribs (usually under 25), and lighter coloration, some shells being entirely white within. It is the common form in New Zealand. Type in the Dominion Museum, Wellington.

In all its characters this subspecies is subject to great variation. At Breaker Bay, Cook Strait, there are found in the brown-algae formation large depressed forms with broad irregular outlines; this is the form called by Suter stella. The largest are found in the vicinity of Wellington City sewer-outlet, and their large size is probably due indirectly to increased organic matter in the water. Sometimes the shells are considerably elevated, approaching corticata.

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The margin of the shell seems readily to adjust itself to the irregularities of the rock-surface on which the animal lives. It is thus seldom in one plane. Occasionally also, one side of the shell, on coming into contact with a projecting piece of rock, stops growth in that direction but continues in others, so that the shell becomes strongly inequilateral or truncated in front or behind. Such shells are found at Breaker Bay, Cook Strait.

It is difficult to describe the variety of colours exhibited by the shells of this subspecies. In few cases only is the outside colour visible, when it is seen to be greenish with brownish radiating lines in the interspaces between the ribs. The inside markings are always some shade of brown or purplish-brown on a white or bluish-white ground. Occasionally there are no markings, the interior being quite white; more frequently there are blotches and radiating lines, while sometimes the whole inside is coloured. There are indications of some relation between the amount of colouring present and the degree of exposure of the shell to the light, for the shells with the least colouring are those found on seaweed-covered rocks near low-tide mark, while those with the inside entirely coloured are small shells without a covering of algae, and living near high-tide mark. Patches of brown colour on the inside generally occur opposite eroded areas on the outside. A similar fact has been observed by Thomson in the genus Cellana. The inside of shells covered with pink Melobesia often has a pinkish tinge.

Reviewing an extensive series of specimens collected at many localities, it seems impossible to define recognizable forms. As may be inferred from the preceding observations, variation is apparently controlled by external factors, such as exposure, light, and food-supply. In this last connection it is to be noted that there is a rough correspondence between the size of the shell and the height of its station above low-tide mark. The following notes on shells from various localities indicate the more conspicuous forms the subspecies takes:—

Sunday Island: One specimen, in no way different from specimens from the north of New Zealand. It is depressed and wide, and covered with Melobesia, with the inside brownish over the whole surface.

Parenga: On rocks near high-tide mark. Little algae on outside; some shells quite free. Interior of all more or less brown, the spatula and margin being darker than the rest. Length of largest shell collected, 17 mm.

Raglan: Shells from the upper part of the intertidal belt have a dark-brown margin and spatula with bluish-white between. Specimens from the barnacle formation lower down are much lighter in colour.

Mount Maunganui: Barnacle formation, between tides. All shells rather dark colour inside, the ground-colour between the spatula and margin being bluish-white. Several of the smaller specimens show seven rays more prominent than the rest.

Stephen Island: In Carpophyllum association. Large wide shells thickly covered with Melobesia. Inside white or pinkish.

Breaker Bay, Cook Strait: The largest shells I have seen come from this locality. They are irregularly ribbed, very rarely seven rays larger than the others. Length, 22 mm.; breadth, 27 mm. In these large specimens the interior is usually white with dark-brownish patches in the central area and sometimes a pinkish margin. Although Suter (Man. N.Z. Moll, p. 73) referred these larger specimens to stella, his description does not cover them, but is merely an amended translation of Lesson's.

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Bionomics.—The subspecies corallina is extremely common in the intertidal belt from high-to low-water mark. It is most abundant on seaweed-covered rocks in the low-tide belt.

With very few exceptions the shells are covered with a thick growth of the coralline alga Melobesia, on which there also occasionally grows tufts of Corallina. In fact, the shells appear to be free from algae only when growing in situations not suited to the growth of seaweed.

Distribution.—Sunday Island, Kermadec Group; Spirits Bay, Parenga, Bay of Islands, Little Barrier Island, Raglan, Mount Maunganui, Napier, Cook Strait (north side), Stephen Island, Lyttelton, Shag Point, Stewart Island (rare), East Cape, and Taumaki Island (Suter). Pliocene of the Wanganui district (Hutton).

(c.)

Subspecies pseudocorticata (Iredale).

Acmaea pseudocorticata Iredale, Trans. N.Z. Inst., vol. 40, p. 379, 1908 (Lyttelton Harbour). Acmaea stella var. pseudocorticata Iredale: Suter, Man. N.Z. Moll., p. 74, 1913.

This form is characterized by its small size, elongate form, lower ribs, and consequently little-crenulated margin. Colour outside greenish with radial brown markings on the interstices between, the ribs, especially near the margin. The inside may be brown, lighter just inside the muscle-scar, or it may be yellowish with black radiating bands outside the muscle-scar.

It differs from the subspecies corticata only in minor characters that one would expect to find in shells living along the upper edge of the intertidal belt. It should not be ranked higher than a subspecies of the species corticata.

Bionomics.—On rocks in the intertidal belt near high-water mark, especially in baths and harbours. It does not support the coralline algae Melobesia, probably because its station is higher than that of the algae.

Distribution.—Lyttelton, Taylor's Mistake, Shag Point, Portobello, Otago Peninsula.

Patelloida (Patelloida) hamiltonensis Chapman and Gabriel.

Patelloida hamiltonensis Chapman and Gabriel, Proc. Roy. Soc. Vict., vol. 36, p. 24, pl. 1, fig. 3, 1923.

Judging by the description and figure, this species would fall into the subgenus Patelloida. It is characterized by about 10 rather prominent radiating ribs, with finer riblets in the interspaces.

Distribution.—Victoria: Muddy Creek (Lower Pliocene-Kalimnan).

Subgenus Collisellina Dall.

Collisellina (section of Collisella) Dall, Amer. Journ. Conch., vol 6, p. 259, 1871. Type: Patella saccharina Linné.

Shell with 7 ribs more prominent than the others, 3 anterior and 4 posterior. Colour predominantly dark, the spatula usually spotted.

Patelloida (Collisellina) saccharina (Linné).

Patelloida saccharina is a polymorphous form with high ribs having a tendency for 7 to be more prominent than the rest. The interior may be entirely white with a black-and-yellow margin, or the spatula may be cream or pale brown variously blotched and spotted, or even entirely dark brown.

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Dentition 2.2.2.2.2, the centrals and inner laterals with broad recurved cusps, the remaining teeth small and probably functionless.

Although Patelloida saccharina occurs under different forms, they appear properly classified as a single species. From the specimens before me I conclude that there are two principal forms—a southern one having a spotted spatula, and a northern one in which the spatula is either white or blotched with brown—but that these two forms merge in the Western Pacific.

Distribution.—From the Andaman Islands to Japan and southward through the Malay Archipelago to tropical Australia from the Monte Bello Islands on the west to Port Curtis on the east. It extends into western Polynesia as far as the Fiji Islands and Samoa, also Funafuti (Ellice Group).

(a.)

Subspecies saccharina (Linné).

Patella saccharina Linné, * Syst. Nat., ed. 10, p. 781, 1758: Reeve, Conch. Icon., pl. 28, f. 72, 1855: Lisshke, Jap. Meeres-Conchyl., p. 113, 1869: Dunker, Index Moll. Man. Jap., p. 155. Patella stellaris Bolten, Mus. Bolt., p. 12, 1798. Patella lanx Reeve, Conch. Icon., vol. 8, pl. 30, f. 82, 1855 (Japan). Acmaea saccharina (Linné): Pilsbry, Man. Conch., vol. 13, p. 49, pl. 36, f. 60–62, 78; pl. 18, f. 31, 32; pl. 24, f. 12, 13 (P. lanx); pl. 42, f. 83 (radula), 1891: Hanley, in Wood's Index Test., 2, ed., p. 185, 1856: Hedley, Mem. Austr. Mus., vol. 3, p. 402, 1899. Collisella saccharina (Linné): Dall, Am. Jour. Conch., vol. 6, p. 259, pl. 15, f. 18 (radula), 1871.

Specimens from the Philippines which I have seen have 7 large ribs with smaller ones in between, the interior is white, the margin yellow, and black patches between the ribs. This form is typical saccharina. In the Japanese specimens described by Reeve as Patella lanx there are numerous nearly equal-sized ribs, but shells from Japan which I have examined have 7 dominant ribs and the interior is spotted or blotched.

Distribution.—Andamans, Philippines, Japan, Funafuti (Hedley).

(b.)

Subspecies stella (Lesson).

Patella Stella Lesson, Voy. “Coquille,” Zool., vol. 2, p. 421, 1830. Patelloida stellaris Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 356, pl. 71, f. 1–4, 1834 (New Ireland). Acmaea saccharina var. stellaris (Q. & G.): Pilsbry, Man. Conch., vol. 13, p. 50, pl. 36, f. 63, 64, 67, 68, 1891. Acmaea saccharina (Linné): Iredale, Proc. Zool. Soc., 1914, p. 670. Patelloida saccharina (Linné): Hedley, Journ. Roy. Soc. W. Aust., vol. 1, p. 36, 1916; Trans. Roy. Geog. Soc. Austr., p. 13, 1918.

Lesson states that his Patella stella came from New Zealand, and Suter refers the common New Zealand species, P. corticata, to Lesson's name. Pilsbry, however, refers Lesson's species to P. saccharina, and this I believe to be the correct course. I have seen no New Zealand shells which could be covered by Lesson's description, which, however, agrees in every particular save the colour of the inside margin with Quoy and Gaimard's Patelloida stellaris. Lesson gives a description of the outside of his shell tallying with the tropical form. The New Zealand species is almost invariably covered with Melobesia, and no colour-pattern is visible. The spatula occasionally bears brown blotches; it is never spotted as Lesson describes. I have no hesitation, therefore, in restoring Lesson's name to the southern form of Patelloida saccharina.

Specimens living in the Ostrea cucullata association on rocks between tides, at Facing Island, Port Curtis, Queensland, have the apex eroded, and

[Footnote] * Linné gave the Barbadoes as the locality for his species, but this was an error. According to Robson, the type locality is the Philippines.

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the ribs numerous and nearly of equal size, though usually 7 are larger than the others. The interior shows a pale-brown spatula dotted with dark brown; outside this it is white or bluish-white with a black-and-yellow banded margin. This appears to me to be the form described by Lesson as Patella stella, and by Quoy and Gaimard as Patelloida stellaris. In some of the Facing Island specimens a portion or even the whole of the spatula may be dark brown, obliterating the spots.

At Levuka, Ovalau, specimens were collected on rocks between tidemarks: they were deeply eroded. Some of the specimens possessed 7 main ribs with quite small ones between, as in the Philippine specimens; in others there were more numerous and more equal-sized ribs. In one specimen the interior was white with a black-and-yellow margin. In most of the others the space between the marginal band and the spatula was bluish-white, while the spatula was pale brown with dark-brown blotches and spots. These specimens seem to bridge over the difference between typical saccharina from the Philippines and typical stella from Port Curtis.

Iredale notes that the Australian form extends along the northern coast of Australia from Monte Bello Islands to Port Curtis. According to me, this form extends farther eastward into the Pacific as well.

Bionomics.—At Port Curtis the subspecies stella occurs abundantly on rocks between tide-marks, in the Ostrea cucullata association, and among algae in rock-pools. At Ovalau, Fiji Islands, it is common on intertidal rocks.

Distribution.—Monte Bello Islands, Camden Sound and Buccaneer Archipelago, Port Essington, Cape York, Port Curtis, New Ireland, Fiji.

Patelloida (Collisellina) latistrigata (Angas). (Text-fig. A.)

As a species Patelloida latistrigata is easily distinguished by the presence of ribs, which in the southern form show 7 more prominent than the rest, while the interior is especially characteristic, the spatula being pale brown, spotted or grained with dark brown and with a white border.

Radula of specimen from Frederic Henry Bay, Tasmania: Centrals with long narrow bases and long pointed projecting dark-brown cusps. Inner laterals with short bases and pointed projecting dark-brown cusps shorter than the centrals. Outer laterals very small. Marginals transparent, with short broad cusps.

Two well-defined subspecies may be recognized.

Distribution.—Tasmania and the south coast of Australia from South Australia to New South Wales.

(a.)

Subspecies latistrigata (Angas). (Text-fig. A.)

Patella latistrigata Angas, * Proc. Zool. Soc., 1865, p. 154 (Aldinga Bay, S. Aust.). Acmaea latistrigata (Angas): Gatcliff and Gabriel, Proc. Roy. Soc. Vic., vol. 21, p. 382, 1908. Helcioniscus latistrigata (Angas): Pilsbry, Man. Conch., vol. 13, p. 143, 1891. Acmaea marmorata Tenison-Woods, Proc. Roy. Soc. Tas., 1875, p. 156, 1876 (South Tasmania); l.c., 1876, p. 53, 1877: Pilsbry, Man. Conch., vol. 13, p. 52, pl. 42, f. 66–68, 1891: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 210, 1906; vol. 36, p. 184, 1912: Tate and May, Proc. Linn. Soc. N.S.W., vol. 26, p. 412, 1901. Acmaea gealei (not Angas): Pritchard and Gatcliff, Proc. Roy. Soc. Vic., vol. 15, p. 197, 1903.

In the ordinary form of the species as it occurs in Tasmania, South Australia, and Victoria the spatula is closely marked with fine radiating

[Footnote] * Vercoe states that this is a half-grown example with broad radial stripes.

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and anastomozing lines, dark brown on a lighter ground. Near the edge of the spatula these lines break up into dots, and the ground-colour becomes pure-white. In many cases 7 ribs are larger than the others, 3 in front of and 4 behind the apex.

The largest specimens I have seen some from South Australia, and measure 24 mm. in length. These were thick shells with high ribs and deeply-eroded apexes. Specimens from Port Phillip show variation in the marking on the spatula. In one there are very fine lines, in another there are large dots.

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Radulae of—A, Patelloida latistrigata (Angas); B, Chiazacmea flammea (Q. & G.); C, C. heteromorpha Oliver; D, Actinoleuca campbelli (Filhol); E, Notoacmea petterdi (Ten.-Woods); F, N. helmsi (Smith); G, N. corrosa Oliver; H, N. tadia Oliver; I, N. scopulina Oliver.

Bionomics.—In Tasmania, in the Derwent Estuary, Patelloida lati-strigata occurs on intertidal rocks near high-water mark, and in the Mytilus planulatus association in the mid-tide belt. These specimens are generally small (under 15 mm. in length), and have the apex eroded.

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Distribution.—South Australia: Streaky Bay and St. Francis Island, eastward to Port Macdonnell (Verco), Aldinga Bay. Victoria: Coast generally, Cape Otway, Cape Schanck, Cape Patterson. Tasmania: Common on the coast generally, Derwent Estuary, Southport.

(b.)

Subspecies submarmorata (Pilsbry).

Acmaea marmorata var. submarmorata Pilsbry, Man. Conch., vol. 15, p. 52, pl. 42, f. 49, 70, 1891 (Port Jackson). Patelloida submarmorata (Pilsbry): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 236, 1924.

In New South Wales this distinct form of the species occurs. It is characterized by the numerous small ribs of nearly even size, the subcentral apex, the large dark spots on the spatula, and its narrow white border. As these spatula characters appear occasionally in Tasmanian and Victorian specimens, and the ribbing is variable in both forms, I consider submarmorata best classed as a subspecies of latistrigata. The largest specimens that I have seen measure 13 mm. in length.

Bionomics.—In New South Wales, on the coast near Sydney, I found the subspecies submarmorata common near high-tide mark and in the barnacle association in the mid-tide belt.

Distribution.—New South Wales: common in the vicinity of Sydney. Queensland (Verco). Victoria: Mallacoota (Iredale).

Genus Chiazacmea n. gen.

Shell smooth, or with low rounded ribs. Colour light with brown rays, a cross-pattern usually evident, spatula dark. Type: Patelloida flammea Q. & G. (Hobart) (as herein defined).

Chiazacmea flammea Q. & G. (Text-fig. B.)

Chiazacmea flammea is a polymorphic species, in which several rather distinct forms may be defined. This circumstance has led to numerous names having been bestowed on it. Characters diagnostic of the species are the elevated form with the apex about the anterior third, the radiating bands of colour usually with a cross-pattern most conspicuous, and the dark spatula.

The radula is here described and figured from a specimen of the subspecies mixta from Corny Point, South Australia. Centrals approximated, broad, ending in wide blunt recurved cusps. Inner laterals wider than the centrals, short, with broad recurved cusps, with the angles truncated and the upper curved margin concave. Outer laterals narrow, sharp-pointed. Centrals and laterals horn-colour with dark-brown cusps. Marginals 2 on each side, small, narrow, transparent.

Distribution.—Tasmania; and extra-tropical Australia from Rottnest Island in Western Australia to Port Curtis in Queensland

(a.)

Subspecies flammea Q. & G.

Patelloida flammea Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 354, 1834 (Hobart). Acmaea flammea (Q. & G.): Tenison-Woods, Proc. Roy. Soc. Tas., 1876, p. 51, 1877; 1877, p. 45, 1878: Pilsbry, Man. Conch., vol. 13, p. 57, pl. 37, f. 78–83, 1891: Pritchard and Gatliff, Proc. Roy. Soc. Vic., vol. 15, p. 196, 1903. Acmaea cantharus (not Reeve): Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 215, 1906. Acmaea mixta (not Reeve): Hedley, Proc. Linn. Soc. N.S.W., vol. 39, p. 713; 1915.

When Quoy and Gaimard described Patelloida flammea they stated: “Il habite en abondance sur le bord de la mer, dans la rade de Hobart

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Town, à Van Diemen. Nous le trouvames aussi sur l'île de Guam, dans l'archipel des Mariannes.” Their figures can be matched quite well by the form commonly found in the intertidal belt of Blackmans Bay, near Hobart. Hedley (Proc. Linn. Soc. N.S.W., vol. 39, p. 713, 1915) states that figs. 17–20 relate to a Guam species, assigns to it the name flammea, and uses mixta for the Tasmanian form. Such a proceeding is, I think, scarcely warranted. Quoy and Gaimard's description evidently refers to the Tasmanian shell, which occurs “en abondance.” Further, there does not appear to be any evidence other than Quoy and Gaimard's statement that a species of Patelloididae occurs in Guam at all. Hedley has not named a species which falls a synonym to his usage of flammea. In any case. seeing that flammea has constantly been used for the Tasmanian species and no other, the proper course is to retain the name for it alone and to rename the Guam shells when authentic specimens are forthcoming.

Since the above was written I note that Iredale (Proc. Linn. Soc. N.S.W., vol. 49, p. 234, 1924) comes to the conclusion that Quoy and Gaimard's name flammea should be retained for a Tasmanian species; but assigns it to the shell generally known as septiformis. I maintain, however, that my usage is correct, for the following reasons: Quoy and Gaimard's description and figures are far more applicable to the species traditionally accepted as flammea than they are to septiformis. The shape of the shell, with the apex high and sometimes subcentral, and the colour-pattern, both inside and outside, are characteristic of the species always regarded as flammea, and not of septiformis. All the figures can be matched quite well. Moreover, it is improbable that Quoy and Gaimard could have missed collecting flammea, which occurs abundantly on rocks near high-tide mark. The other species, septiformis, occurs under stones at low-tide mark, and, as the range of the tide at Hobart is only 4 ft. and low tide occurs only once in every twenty-four hours, it would more likely be the species to be overlooked. Further, Dr. Lamy has, at my request, examined the types of Patelloida flammea. They comprise six shells. Exteriorly five have brown and whitish rays, while one bears whitish flames. These characters are distinctive of Tasmanian examples of the shell here accepted as flammea. Interiorly five of the types are bluish except the central portion and have a dull border, and agree with pl. 71, fig. 17, of the “Astrolabe” Atlas. Such a type of coloration can be matched in shells of flammea with rayed exteriors, whereas in septiformis when a shell is rayed externally it is also rayed within, while the spatula in adult Tasmanian examples is usually little different from the remainder of the interior, and the outside is uniformly dark. One of the types shows a brownish interior on which are yellowish rays (like pl. 71, fig. 19, of the “Astrolabe” Atlas), and, comparing this with shells I sent him from near high-tide mark, Derwent Estuary, Tasmania, Dr. Lamy reports that this shell “rapproche le plus votre echantillon qui peut donc être rapporte au P. flammea.” While, therefore, it is possible that Quoy and Gaimard's Patelloida flammea is a mixture of two species, I am convinced that some of the type specimens belong to the species here defined.

The first form of flammea that I recognize is that in which the shell is thin, moderately high, apex well forward, back slope slightly convex, front slightly concave. The colour outside is usually banded dark and light. Sometimes the bands are broken up into a zigzag pattern. The inside has a dark spatula; outside this it is generally lighter, with dark bands often showing a cross with broad rays amongst them. Shell usually smooth, sometimes with faint rounded ribs.

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Bionomics.—Common in the Derwent Estuary, Tasmania, on rocks above half-tide mark. The shells are usually clean and well marked.

Distribution.—Tasmania: Derwent Estuary, Southport. South Australia: Robe, Macdonnell Bay. Victoria: Port Phillip, Cape Otway.

(b.)

Subspecies conoidea Q. & G.

Patelloida conoidea Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 355, 1834 (King George Sound). Acmaea conoidea (Q. & G.): Verco, Trans. Roy. Soc. S Aust., vol. 36, p. 198, 1912: Pilsbry, Man. Conch., vol. 13, p. 53, pl. 37, f. 84, 85, 1891. Patelloida conoidea Q. & G.: Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916. Patella insignis Menke, Moll. Nov. Holl. Spec., p. 34, 1843 (Western Australia). Radiacmea insignis (Menke): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924. Patelloida mixta (Reeve): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916. Acmaea flammea (not Q. & G.): Verco, Trans. Roy. Soc. S. Aust., vol. 36, p. 198, 1912.

The shell described by Quoy and Gaimard was very high, the altitude (11 mm.) being nearly as great as the length (13 mm.) Verco (Trans. Roy. Soc. S. Aust., vol. 36, p. 198, 1912) records shells of similar type but lower altitude from Ellensbrook and Rottnest Island, Western Australia, and suggests that Quoy and Gaimard's shell was probably a monstrosity, and that both it and Verco's own specimens are variants of flammea. On looking over eroded shells from various localities, one may easily find specimens which match Quoy and Gaimard's type in all characters save altitude. One of Verco's shells from Rottnest Island is fairly elevated, being 22 mm. in length and 18 mm. in height. I have little doubt then that Verco's surmise is correct, and that Quoy and Gaimard's Patelloida conoidea is an unusually high example of the common eroded Western Australian flammea. It certainly is not conspecific with the small Australian and Tasmanian species which have been referred to it.

The Western Australian form of Chiazacmea flammea may conveniently be kept as a subspecies. It is so regarded by Iredale, who applies to it Menke's name insignis. But if I am right in considering that Quoy and Gaimard's name conoidea refers to this form, then the synonymy will stand as above given. It apparently agrees with the first and third varieties mentioned by Verco in Trans. Roy. Soc. S. Aust., vol. 30, p. 213, 1906.

The subspecies conoidea is characterized by the moderately elevated form, arched slopes, broad radiating ridges, and crenulate margin. It is usually eroded, when the ridges may be obsolete. The colour shows radiating brown lines usually only evident on the margin, with the cross-pattern more or less indicated.

Distribution.—Western Australia from Rottnest Island southward and along south coast. South Australia: Robe.

(c.)

Subspecies mixta (Reeve). (Text-fig. B.)

Patella mixta Reeve, Conch. Icon., pl. 39, f. 129, 1855 (Port Phillip). Acmaea jacksoniensis var. mixta (Reeve): Pilsbry, Man. Conch., vol. 13, p. 58, pl. 35 f. 32, 33, 1891. Patelloida mixta (Reeve): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 234, 1924. Acmaea crucis Tenison-Woods, Proc. Roy. Soc. Tas., 1876, p. 52, 1877 (Tasmania). Acmaea flammea (Q. & G.): Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 212 (second and fourth varieties), 1906; vol. 36, pp. 183, 1912. Acmaea inradiata (not Reeve): Hedley, Proc. Linn. Soc. N.S.W., vol. 39, p. 712, 1915.

I have not seen the type, but Mr. Tomlin has lent me a specimen from Port Phillip which he states is extremely like the type. It is smooth outside with radiating brown marks and spots. Inside the spatula is dark

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brown with a white centre; outside it is white with a yellowish margin. Brown rays, 1 in front and 3 or 4 behind, with short marginal ones at the side, indicate the crucis pattern. It is very similar to specimens from Wool Bay, South Australia.

The third form of flammea is a thick shell, smooth or with fine radiating ribs, high and with the apex more central than in the subspecies flammea. Outside, if uncorroded, it shows a dark cross on a light ground. Inside the spatula is dark with a white centre. Between the spatula and the margin it is white, with the rays of the cross dark brown. Many variations occur, and intermediates between this and other subspecies are common enough. It is distinguished from the subspecies conoidea mainly by the ribs being finer or absent and the frequent appearance of a well-defined cross.

Bionomics.—In the Derwent Estuary, Tasmania, this form occurs in the Mytilus planulatus association in the low-tide belt. The shells are generally eroded over the whole outer surface.

Distribution.—Tasmania; South Australia; Victoria.

(d.)

Subspecies cavilla (Iredale).

Radiacmea insignis cavilla Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924.

This form shows the crucis pattern very clearly, but is distinguished from the subspecies mixta by its smaller size and regular close radiating ribs, about 50, with the interspaces narrower than the ribs. The ribs are finer than those of conoidea but coarser than those of mixta. Length, 13 mm. Iredale has named but inadequately described this subspecies, and has not indicated where the type specimen is deposited.

Bionomics.—Living on intertidal rocks ranging from near high-tide mark to low-tide mark, where I found it attached to shells of Balanus. Recorded by Iredale on shells of Turbo stamineus below low-tide mark.

Distribution.—New South Wales.

(e.)

Subspecies mimula Iredale.

Patella jacksoniensis Reeve, Conch. Icon., vol. 8, pl. 39, f. 127, 1855 (Port Jackson) (not Patella jacksoniensis Lesson). Tectura jacksoniensis (Reeve): Angas, Proc. Zool. Soc., 1867, p. 220. Acmaea jacksoniensis (Reeve): Pilsbry, Man. Conch., vol. 13, p. 58, pl. 42, f. 71–75, 1891. Notoacmea mixta mimula Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924.

This subspecies is about the same size as cavilla, but is smooth, with the outside usually eroded. Outside showing greenish and brown bands. Inside shining, with broad dark-brown and pale-yellow radiating bands.

Bionomics.—Intertidal in the Ostrea cucullata association, Sydney Harbour.

Distribution.—Sydney Harbour, N.S.W.; Blackmans Bay, Tasmania.

(f.)

Subspecies queenslandiae n. subsp.

Description of type specimen, from Gladstone (in Dominion Museum): Shell conical, depressed, apex subcentral, slopes straight, plane of base arched, broadly elliptical. Outer surface smooth, eroded; interior—spatula porcellaneous, white with a few brown blotches, remainder shining, white, with about 16 radiating brown bands darkest at the margin and each consisting of several lines. Length, 14 mm; breadth, 11 mm.; height, 5.5 mm.

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Bionomics.—Living on rocks between tides in the Ostrea cucullata association.

Distribution.—Gladstone, Port Curtis.

The present subspecies is close to mixta, differing in its broad depressed form, and in the greater amount of white in the interior. In some specimens the cross-pattern is indicated by the colour-bands at the ends and sides being darker than the others.

Chiazacmea mufria (Hedley).

Acmaea mufria Hedley, Proc. Linn. Soc. N.S.W., vol. 39, p. 713, pl. 31, f. 50–52, 1915 (Svdney Harbour). Radiacmea mufria (Hedley): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924.

This little species has a narrow elevated shell with 20 to 30 low broad ribs. It is buff irregularly rayed with brown. Length, up to 8 mm.

The shell in form and texture somewhat resembles that of Chiazacmea flammea subsp. mixta, hence I have placed it near that species. The characters of the radula are unknown.

Bionomics.—Living among the annelid Galeolaria caespitosa between tide-marks, Middle Harbour, Port Jackson.

Distribution.—New South Wales: Balmoral Beach, Middle Harbour, Wreck Bay, Twofold Bay.

Chiazacmea heteromorpha n. sp. (Plate 99, fig. 1; and text-fig. C.)

Description of type specimen from Facing Island (type in Dominion Museum): Shell elevated, conical, apex a little in advance of the centre, the sides convex, the anterior slope considerably steeper than the posterior, the surface rough, the apical portion eroded, but no ribs. Colour of uneroded portion dark brown. Margin irregular in outline, narrowed in front, and truncated anteriorly and posteriorly, the right side expanded behind the apex, the left side fairly regular. Plane of base irregular, evidently in adjustment to the rock-surface. Interior margin glossy, spatula porcellaneous. Spatula white with a brownish centre, margin jet-black, between these pale bluish-brown crossed by 6 broad black bands. Length, 18 mm.; breadth, 16 mm.; height, 8 mm.

Range of variation: This species undergoes remarkable changes in its life-history. The young shell is perfectly regular in form, narrowed in front, apex in the anterior third, sides straight, finely ribbed, yellow with 8 broad black rays. Spatula dark brown. As growth proceeds the margin expands irregularly in adjustment to the irregularities of the rock-surface and the original regular young shell becomes the eroded apex of the adult. The colour-bands can be distinguished only in the marginal area of the inside, and occasionally on the outside. Generally the anterior 3 bands of the young shell, which are narrower than the others, are displaced by a single broad band in the adult shell, thus giving 6 as the normal number of the adult. The spatula is sometimes obscurely rayed or spotted with brown. Half-grown shells clearly show the changing characters.

Description of radula: Centrals with long narrow blunt-pointed cusps. Inner laterals with broad rounded cusps; outer laterals with narrow rounded cusps. Marginals with broad cusps projecting inwards.

Bionomics.—Living on rocks between tide-marks in the Ostrea cucullata association and above.

Distribution.—Facing Island, Queensland.

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Genus Asteracmea n. gen.

Shell minute, translucent, apex subcentral or anterior, sides straight or slightly arched, smooth or with minute radiating striae. In most species the shells have radiating pink bands. Type: Helcioniscus illibrata Verco.

The radula of A. illibrata has the formula 2.2.2.2.2. Centrals approximate, laterals posterior and in a row, the inner larger than the outer, marginals narrow.

The five species I have grouped together under the above name seem to be allied. The only one in which the animal is known is named as type. The characters of the radula and shell bring it clearly within the family Patelloididae. Verco states that his illibrata has an incomplete branchial cordon, nothing being said of a plume. I have, however, in placing the genus Asteracmea near Patelloida relied on the radula characters which are fully described and figured.

The species range down to 100 fathoms, and are found from Western Australia to New Zealand.

Asteracmea illibrata (Verco).

Shell small, conical, smooth, apex central or subcentral, usually with 8 pink rays on the lower half of the shell.

Distribution.—Western Australia; South Australia; New South Wales; Tasmania.

(a.)

Subspecies illibrata (Verco).

Helcioniscus illibrata Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 205, pl. 10, f. 6–14, 1906 (Spencer Gulf); l.c., vol. 36, p. 181, 192, 1912.

Shell nearly as high as long, apex central, pink with 8 white rays on the lower half.

Distribution.—Western Australia: King George Sound, Ellensbrook, Yallingup, Bunbury, Rottnest Island. South Australia: Spencer Gulf; south of Cape Wills (100 fathoms); off St. Francis Island (15–20 fathoms).

(b.)

Subspecies mellila (Iredale).

Notoacmea suteri (not Iredale): May, Proc. Roy. Soc. Tas., 1915, p. 78; Checklist Moll. Tas., p. 47, pl. 22, f. 12, 1921. Parvacmea illibrata mllila Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 242, 1924 (Tasmania).

Shell moderately elevated, apex in front of the centre, usually with 8 pink rays. Differs from the subspecies illibrata in the lower altitude and less centrally placed apex.

Distribution.—Tasmania; Twofold Bay, Sydney, N.S.W.

Asteracmea suteri (Iredale).

Acmaea roseoradiata Suter, Proc. Mal. Soc., vol. 7, p. 317, pl. 27, f. 9, 10, 1907 (Port Pegasus, Stewart Island; type in Wanganui Museum); Man. N.Z. Moll., p. 65, pl. 5, f. 8, 1913 (not A. roseoradiata Smith). Notoacmea suteri Iredale, Trans. N.Z. Inst., vol. 47, p. 428, 1915 (new name for A. roseoradiata Suter).

Shell elevated, conical, apex subcentral, upper portion with subobsolete radiate striae, lower portion with indistinct low riblets. Pink with 10 broad white rays on lower portion. This species appears to differ from A. illibrata in having 10 pink rays.

Distribution.—New Zealand: Port Pegasus (18 fathoms), Dusky Sound (30 fathoms), off Taumaki Island (10 fathoms), Snares (50 fathoms).

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Asteracmea crebrestriata (Verco).

Nacella crebrestriata Verco, Trans. Roy. Soc. S. Aust., vol. 28, p. 144, pl. 26, f. 20, 21, 1904; l.c., vol, 30, p. 208, 1906; l.c., vol. 36, pp. 183, 195, 1912, Nacella crebrestriata Verco, var. roseoradiata Verco, Trans. Roy. Soc. S. Aust., vol. 36, p. 195, 1912 (Guichen Bay, S. Aust.).

Shell moderately elevated, apex subcentral, numerous radial riblets. Translucent, with white markings or 15–16 pink radiating bands.

Distribution.—Western Australia: King George Sound, Yallingup, Rottnest Island. South Australia: off Cape Borda (55 fathoms), Port Sinclair, St. Francis Island, Guichen Bay.

Asteracmea stowae (Verco).

Nacella stouae Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 209, pl. 10, f. 4, 5, 1906; l.c., vol. 36, pp. 183, 195, 1912.

Shell depressed, apex anterior, numerous fine radiating striae, translucent, with 16 pink radiating bands.

Distribution.—Western Australia: King George Sound, Bunbury, Rott nest Island. South Australia: Kingston, St. Francis Island, Port Macdonnell, Kings Point.

Asteracmea axiaerata (Verco).

Patella axiaerata Verco, Trans. Roy. Soc. S. Aust., vol. 36, p. 193, pl. 15, f. 3, 4, 1912 (Rottnest Island). (Type in Verco's collection.)

Shell conical, smooth, apex subcentral, height about half the length, white with 10–18 yellow radial bands with golden axial hair-lines in them.

Distribution.—Western Australia: King George Sound, Rottnest Island.

Genus Radiacmea Iredale.

Radiacmea Iredale, Trans. N.Z. Inst., vol. 47, p. 427, 1915. Type: Acmaea cingulata Hutton.

This genus may be defined as including those species possessing radially-ribbed porcellaneous shells and radulae with the formula 0.2.2.2.0. The teeth of Radiacmea rubiginosa, the only species in which the radula is known, are short and blunt-pointed, the centrals are in juxtaposition and in advance of the laterals, which are nearly of equal size and in two pairs, the outer pair being posterior to the inner. They are thus disposed in two rows diverging posteriorly from the centrals.

Conchologically the species are not to be distinguished from those of Patelloida, which have regularly-ribbed shells. The teeth, however, are quite different, and recall in disposition those of Tectura.

Radiacmea comprises 3 species from the New Zealand area, ranging from the Bay of Islands and the Chatham Islands southward to Macquarie Island.

Radiacmea inconspicua (Gray).

Radiacmea inconspicua is distinguished by the radiating ribs with wide interspaces. About 20 reach the apex, but at the margin there may be double this number. The position of the apex and the contour of the base differs in the two subspecies. Colour inside pinkish, the centre whitish or greenish; usually there are radiating bifurcating lines of a darker pink.

Description of radula from a specimen from Lyall Bay, Cook Strait: The radula-plates are rectangular with the outer and anterior sides sinuated.

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The teeth, one pair of centrals and two of laterals, arranged in two diverging rows, the centrals being in contact and the outer laterals wide apart. Cusps short and blunt, all of nearly equal size.

Distribution.—New Zealand, from the Bay of Islands and Little Barrier Island southwards to Otago Peninsula; Chatham Islands.

(a.)

Subspecies inconspicua (Gray).

Patella inconspicua Gray, in Dieffenbach's Travels N.Z., vol. 2, p. 244, 1843 (type in British Museum). Radiacmea inconspicua (Gray): Iredale, Proc. Linn. Soc. N.S.W., vol.49, p. 237, 1924. Acmaea cingulata Hutton, N.Z. Jour., vol. 1, p. 477, 1883 (Dunedin; type in Canterbury Museum); Trans. N.Z. Inst., vol. 16, p. 215, pl. 11, f. 5 (radula), 1884; Proc. Linn. Soc. N.S.W., vol. 9, p. 372, 1884: Pilsbry, Man. Conch., vol. 13, p. 53, 1891: Suter, Proc. Mal. Soc., vol. 7, p. 316, pl. 27, f. 3–5, 1907; Man. N.Z. Moll., p. 63, pl. 5, f. 6, 1913. Acmaea rubiginosa (Hutton): Iredale, Trans. N.Z. Inst., vol. 40, p. 376, 1908: Bucknill, Sea-shells N.Z., p. 13, pl. 5, f. 7, 1924.

Shell usually depressed, elliptical, often narrowly so, apex about the anterior fourth. About 25–30 principal ribs, usually with 1 or 2 smaller ribs in each interspace towards the periphery, also with concentric growth-striae

I have found very little variation in the shell other than in the intensity of the pink colouring, which varies from a brownish-pink in some young shells through lighter shades.

The animal is white, the foot yellowish, the mouth orange. The edge of the mantle shows more or less green, darkest behind the head. On removing the shell the buccal mass is pink and the yisceral mass deep green.

Bionomics.—The subspecies inconspicua is fairly common on the coralline-covered rock-surfaces in the brown-algae formation, and on the shells of Haliotis iris and H. australis in the low-tide belt. It is easily overlooked, as the shells are invariably covered with a growth of pink Melobesia with sometimes tufts of Corallina in addition. On removing the shell it is found that it exactly fits in the depression in the surrounding Melobesia, which covers the rock or Haliotis shell.

Distribution.—Bay of Islands (Suter); Little Barrier Island; Mount Maunganui; East Cape (Suter); Cook Strait; Banks Peninsula; Otago Peninsula; Shag Point; Taumaki Island, in 10 fathoms (Suter); Taieri Beach.

(b.) Subspecies rubiginosa (Hutton).

Fissurella rubiginosa Hutton, Cat. Marine Moll. N.Z., p. 42, 1873 (Chatham Islands). Patella rubiginosa Hutton, Jour. Conch., vol. 26, p. 38, 1878; Man. N.Z. Moll., p. 110, 1880. Acmaea rubiginosa Hutton, Proc. Linn. Soc. N.S.W., vol. 9, p. 372, 1884: Suter, Proc. Mal. Soc., vol. 7, p. 315, pl. 27, f. 1, 2, 1907: Suter, Man. N.Z. Moll., p. 65, pl. 5, f. 9, 1913. Glyphis rubiginosa (Hutton): Pilsbry, Man. Conch., vol. 12, p. 216, 1890.

In the type collection in the Dominion Museum are three specimens from the Chatham Islands. None agree in measurements with Hutton's description. One specimen, however, a water-worn and bleached shell has an anterior callus partly detached, while the apex outside is worn through. This may have led Hutton to place the species in the genus Fissurella. Hutton afterwards transferred it to Patella,

Shell moderately elevated, broadly elliptical, apex subcentral to the anterior third, acute. About 20 principal ribs with 1 or 2 smaller ribs in each interspace towards the periphery, also with concentric growth-striae.

This subspecies differs from the New Zealand form in its broader outline, more central apex, more elevated form, and more prominent ribs. These,

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however, being variable characters in each subspecies, I class both under the same species.

The largest shell I have seen measures 17 mm. in length.

Bionomics.—Young specimens were found living under stones in rock-pools at Red Bluff.

Distribution.—Chatham Island.

Radiacmea intermedia (Suter).

Acmaea intermedia Suter, Proc. Mal. Soc., vol. 7, p. 316, pl. 27, f. 6–8, 1907 (near Bounty Islands, in 50 fathoms); Man. N.Z. Moll., p. 64, pl. 5, f. 7, 1913.

Only known from dead shells, and from one locality. It appears to be allied to R. macquariensis, a species which I have not seen, but of which Hedley has published a good description and figure.

The shells are small, up to 11 mm. in diameter, conical, with the apex at the anterior third, and with 25–50 fine radiating riblets. It is light-brownish with white ribs and a dark spatula.

Radiacmea macquariensis Hedley.

Radiacmea macquariensis Hedley, Rep. Aust. Ant. Exp., Zool., vol. 4, pl. 1, p. 41, 1916.

Found on intertidal rocks, Macquarie Island, by Mr. H. Hamilton. Hedley compares this species with campbelli of Filhol, but that species, as proved by the radula, belongs to a different genus.

The main characters of Radiacmea macquariensis are the regularly conical form with the apex about the anterior third, the numerous (about 60) depressed radial riblets, and the pinkish coloration. Length, 12 mm.

Genus Naccula Iredale.

Naccula Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 328, 1924. Type; Patellonda punctata Q. & G.

Naccula comprises a single species characterized by its small hyaline shell with anterior apex, and especially by the radula, which has the cutting-edges of the teeth in two diverging lines. Teeth 0.2.2.2.0.

Iredale's guess that this species would form a distinct genus has proved to be correct, though his method of founding new names under such circumstances can scarcely be called scientific.

Distribution.—Western Australia, South Australia.

Naccula punctata (Q. & G.).

Patelloida punctata Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 365, pl. 71, f. 40–42, 1884 (King George Sound): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916. Acmaea punctata (Q. & G.): Pilsbry, Man. Conch., vol. 13, p. 59, pl. 77, f. 89, 1891: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 214, 1906 (this record doubtful—the radial sculpture suggests that the shells were the young of N. septiformis). Nacella parva Angas, Proc. Zool. Soc., 1878, p. 862, pl. 54, f. 12 (South Australia): Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 208, 1906; l.c., vol. 36, pp. 183, 194, 1912. Nacella compressa Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 208, pl. 8, f. 11, 12, 1906 (Investigator Strait, S. Aust.). Naccula punctata (Q. & G.): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 238, 1924.

Shell depressed, apex forward, anterior slope concave, posterior convex, smooth or with fine concentric growth-lines. Horn-colour with an axial line of blue spots. Ratio of width to length variable.

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Radula: Centrals and inner laterals having the cusps with broad cutting faces in two lines diverging from the centre of the radular ribbon to each side, thus apparently forming a scraping organ. Outer laterals small.

Bionomics.—Living on Zostera, Lucky Bay.

Distribution.—Western Australia: King George Sound, Lucky Bay, Bunbury, Geographe Bay, Fremantle. South Australia: Holdfast Bay, Aldinga Bay, Fowler's Bay, Scales Bay, St. Francis Island, Investigator Strait.

Verco dredged specimens at various depths down to 35 fathoms, but does not state whether they were living or not.

Genus Actinoleuca n. gen.

High conical shells with straight sides and subcentral apex. Finely and evenly ribbed. Texture of shell porcellaneous throughout like that of Radiacmea. In the radula of A. campbelli the lateral teeth are in a transverse row posterior to the centrals. Type: Patella campbelli Filhol.

The species here associated form a well-defined and distinct group approaching Radiacmea in shell-characters and Notoacmea in the disposition of the teeth of the radula. One is a deep-water form whose animal has not yet been described, another is a littoral species, the third is an Oligocene fossil.

Actinoleuca campbelli (Filhol). (Text-fig. D.)

Patella campbelli Filhol, Compt. Rend., vol. 91, p. 1095, 1880 (Campbell Island; type in Mus. His. Nat. Paris); Miss. Is. Camp., p. 530, 1885. Acmaea campbelli (Filhol): Suter, Proc. Mal. Soc., vol. 7, p. 321, pl. 27, f. 19–21, 1907; Man. N.Z. Moll., p. 66, pl. 5, f. 10, 1913: Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924.

Notoacmea campbelli is related to N. calamus. It is, however a much smaller shell, uniformly pink in colour. It is an elevated conical species with an acute apex. The sculpture consists of numerous fine radiating riblets.

Radula: Centrals approximate, with short rounded cusps; laterals similar in shape and size to the centrals.

Bionomics.—Actinoleuca campbelli is found living on shells of Cantharidus pruninus, which lives on seaweed growing on coastal rocks at Ross Island, Auckland Islands. Odhner records this species from Campbell Island as on Macrocystis.

Distribution.—Campbell Island; Auckland Islands.

Actinoleuca calamus (Crosse and Fischer).

Patella calamus Crosse and Fischer, Journ. de Conch., 1864, p. 348; 1865, p. 42, pl. 3, f. 7, 8 (Port Lincoln, South Australia). Acmaea calamus (C. & F.): Angas, Proc. Zool. Soc., 1865, p. 186: Pilsbry, Man. Conch., vol. 13, p. 54, pl. 37, f. 3, 4, 1891: Pritchard and Gatliff, Proc. Roy. Soc. Vic., vol. 15, pp. 197, 1903: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 211, 1906; vol. 36. pp. 184, 199, 1912. Acmaea calamus (C. & F.) var. polyactina Verco, Trans. Roy. Soc. S. Aust., vol. 36, p. 184, pl. 15, f. 1, 2, 1912 (Gulf St. Vincent). Patelloida calamus (C. & F.): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916: May, Check-list Moll. Tas., p. 46, pl. 22, f. 2, 1921. Radiacmea calamus (C. & F.): Iredale, Proc. Linn. Soc. N.S. W., vol. 49, p. 236, 1924.

A well-marked species, distinguished by the high conical form, subcentral acute apex, straight sides, and very fine radiating riblets. White, more o [ unclear: ]

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less ornamented with brown spots or radiating bands. Some shells are chestnut-brown.

Distribution.—Verco records this species as taken alive in Spencer Gulf, South Australia, at depths ranging from 5 to 17 fathoms. It is apparently not uncommon in shallow water off the south coast of Australia, from Western Port, Victoria, to Geraldton, Western Australia. Also found in Tasmania, and at Twofold Bay, New South Wales.

Actinoleuca multiradialis (Chapman and Gabriel).

Patelloida multiradialis Chapman and Gabriel, Proc, Roy. Soc. Vict., vol. 36, p. 24, pl. 1, fig. 4, 3, fig. 29, 1923.

This species is stated to be an ally of A. calamus, differing in the more depressed form of the shell, rounder outline, and more scaly character of the ribs.

Distribution.—Victoria: Balcombian (Oligocene), towards the upper part of the Clifton Bank.

Genus Notoacmea Iredale.

Notoacmea Iredale, Trans. N.Z. Inst., vol. 47, p. 428, 1915. Type: Patelloida pileopsis Q. & G.

Notoacmea may be defined as including those species possessing shells having the inner layer thin and hyaline, and the outer (when present) more shelly. The apex is usually forward, and the posterior slope convex. Besides the characters of the shell, they are especially distinguished by the radula, in which the centrals and inner laterals are generally long, curved, and pointed, and stand erect in the basal ribbon. The outer laterals are usually small and apparently functionless.

The genus comprises species distributed over the shores of southern and eastern Australia, Tasmania, and New Zealand. It occurs chiefly in the intertidal belt, ranging from the upper limit of the waves to low-tide mark.

The species here included in the genus Notoacmea may be ranged under five subgeneric groups—Notoacmea, Parvacmea, Conacmea, Thalassacmea, and Subacmea.

Subgenus Notoacmea Iredale.

Shell with the apex well forward, the posterior slope convex, the anterior straight. The inner layer generally translucent porcellaneous, the outer of a coarser texture and dark-coloured, usually tessellated.

Notoacmea (Notoacmea) pileopsis (Q. & G.).

As a species Notoacmea pileopsis may be defined as including shells of elliptical shape, forward apex, sometimes situated above the anterior margin, concave anterior slope, the highest point being behind the apex. The shells may be quite smooth except for concentric growth-lines, or have fine radiating lines or prominent ribs.

Outside the colours are brown and green, tessellated; inside the spatula is dark brown, surrounding this it is bluish-white, while the border is dark brown, more or less marked with yellow.

In the radula (in the subspecies sturnus) the centrals have long bases and long pointed cusps projecting at right angles to the basal plate; the inner laterals have also long projecting pointed cusps; the outer laterals are small.

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Notoacmea pileopsis is a decidedly dimorphic and less markedly polymorphic species. So different are its forms that it is difficult to believe the two found in the northern portion of New Zealand belong to the same species. Suter, indeed, included the species in three places in his Manual Yet one form may be found passing into another under environmental changes. The form with prominent ridges appears to be but an epharmonic varient of the one with fine lirae.

Reviewing the subspecies in connection with their geographical distribution, it will be observed that from the sturnus form they differentiate from south to north into two other very distinct types. It is as though the original form of the species was the smooth sturnus type, with its headquarters in Otago and its outposts extending northwards to Waipara and southward to Macquarie Island. A small section in Campbell Island developed distant radiating lirae. From Banks Peninsula northward the species developed close radiating lirae, with the shells increasing in size and relative width towards the north. In exposed situations this form developed strong ribs, an obvious device to strengthen the shell. This ribbed form then appears to have developed along a line of its own parallel to that of its parent, so that in all characters except the general type of coloration the subspecies pileopsis and cellanoides are perfectly distinct. Their habitats, too, are different. This interpretation of the course of evolution of the forms of pileopsis may be expressed diagramatically as under:—

(a.)

Subspecies pileopsis (Q. & G.).

Patelloida pileopsis Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 359, pl. 71, f. 25–27, 1924 (Bay of Islands): Deshayes, in Lamarck's Hist. Nat. Anim. s. Vert., ed. 2, vol. 7, p. 550, 1836. Tectura pileopsis (Q. & G.): Hutton, Cat. Marine Moll. N.Z., p. 43, 1873; Jour. de Conch., vol. 26, p. 36. Acmaea pileopsis (Q. & G.): Hutton, Man. N.Z. Moll., p. 88, 1880: Pilsbry, Man. Conch., vol. 13, p. 57, pl. 37, f. 90–92, 1891: Suter, Proc. Mal. Soc., vol. 7, p. 319, pl. 26, f. 15–16, 1907; Man. N.Z. Moll., p. 71, pl. 7, f. 4, 1913: Hutton, Proc. Linn. Soc. N.S.W., vol. 9, p. 373, 1884: Bucknill, Sea-shells N.Z., p. 13, pl. 5, f. 6, 1924.

The subspecies pileopsis is narrowly to broadly elliptical, depressed when young, but old specimens become considerably elevated through the downward growth of the margins. The surface is finely and closely radiating lirate. Outside dark, tessellated or radiately marked; inside—spatula dark brown surrounded by bluish-white, margin black with few yellow markings. Length, 28 mm.; breadth, 25 mm.; height, 12 mm. (specimen from Mount Maunganui).

Bionomics.—This subspecies is common in the upper portion of the intertidal belt. The shells are rather thin, with sharp edges, and are usually found in crevices or under ledges—that is, in sheltered places.

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Sometimes they are found above the limits of ordinary high tides. Suter states that they are found in stations protected from rain: this may be so, but it is probable that it is the drying effect of exposure to the sun that the animal endeavours to avoid. The largest shells I have always found in sheltered situations, and in these stations the shells are the least eroded. The shells found on the exposed rocks of Island Bay, Cook Strait, are small, generally under 15 mm. in length, dark-coloured within and without, and with the greater portion of the outer surface eroded. Specimens from Crater Bay, White Island, near where a stream containing hydrochloric acid enters, have thick shells with the outer surface much eroded.

May named and figured but did not describe this species. No mention is made of a type specimen.

Distribution.—Common on the coast as far south as Banks Peninsula: Tom Bowling Bay, Bay of Islands, Little Barrier Island, Mount Maunganui, Cook Strait, Maunganui Bluff, Manukau Head, Raglan, Stephen Island, Waipara, Banks Peninsula.

(b.)

Subspecies sturnus (Hombron and Jacquinot).

Patella sturnus H. & J., Ann. Sci. Nat., ser. 2, vol. 16, p. 191, 1841. Patelloida antarctica H. & J., l.c., p. 192, 1841 (Auckland Island): Pilsbry, Man. Conch., vol. 13, p. 157, 1891. Patella cantharus Reeve, Conch. Icon., vol. 8, pl. 40, p. 131, 1855 (New Zealand). * Nacella cantharus (Reeve): Hutton, Cat. Marine Moll. N.Z., p. 46, 1873. Tectura cantharus (Reeve): Hutton, Jour. Conch., vol. 26, p. 36. Acmaea cantharus (Reeve): Hutton, Man. N.Z. Moll., p. 88, 1880: Pilsbry, Man. Conch., vol. 13, p. 55, pl. 37, f. 1, 2, 1891: Suter, Proc. Mal. Soc., vol. 7, p. 320, pl. 27, f. 17–18, 1907: Iredale, Trans. N.Z. Inst., vol. 40, p. 376, 1908: Suter, Man. N.Z. Moll., p. 66, f. 1, 1913: Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924: Bucknill, Sea-shells N.Z., p. 11, 1924. Acmaea pileopsis (Q. & G.): Hutton, Trans. N.Z. Inst., vol. 15, p. 127, pl. 15, f. M. (dentition), 1883: Iredale, Trans. N.Z. Inst., vol. 47, p. 429, 1915: Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924.

Shell narrow-elliptical, the posterior slope uniformly curved so that the shell is neither so depressed when young nor so elevated when old as in the subspecies pileopsis. Surface smooth except for connected growth-lines. Outside conspicuously tessellated, margin inside yellow and black. Length, 25 mm.; breadth, 19 mm.; height, 10 mm. (Shag Point).

Bioriomics.—Common on rocks in the upper half of the intertidal belt, ascending above high-tide mark in damp situations exposed to sea-spray.

Distribution.—South coast of Banks Peninsula, Shag Point, Otago Peninsula, Stewart Island, Snares (Suter), Auckland Island, Campbell Island, Bounty Island, Macquarie Island, Preservation Inlet (Bucknill).

(c.)

Subspecies cellanoides n. subsp. (Plate 99, fig. 2.)

Description of type from Little Barrier Island (in the Dominion Museum): Shell narrow-elliptical, slightly irregular in outline. Anterior slope concave, posterior arched, apex the highest or nearly the highest point. The whole shell strongly radiately ribbed, 28 to 36 in number, those on posterior slope being largest. Outside tessellated green and brown; inside—spatula

[Footnote] * This name has been generally used for a species found in Tasmania. Iredale in 1908 pointed out (Trans. N.Z. Inst., vol. 40, p. 376) that it refers to a New Zealand species and is a synonym of the species pileopsis. There can be little doubt as to the correctness of Iredale's conclusion; in fact, he has since confirmed it by an examination of the type specimen. Reeve's figure agrees with the New Zealand form, and differs from the Tasmanian shell in practically every point that separates the New Zealand and Tasmanian forms.

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dark brown surrounded by bluish-white, margin dark brown with yellow cross-bands.

From Cook Strait to Banks Peninsula this form appears to be merely a variant of pileopsis, differing only in the possession of ribs, and occurring with the species. In the north, however, it differs entirely from the typical form at all stages of growth, and occurs on exposed rocks, while pileopsis proper occurs in sheltered situations.

Bionomics.—The subspecies cellanoides in the northern portion of New Zealand, with its thickened shell with strong ridges, is well adapted to live in exposed situations. It is found in the barnacle formation from half-tide mark upwards. At “White Island, under the intluence of hydrochloric acid, it assumes a large size (length, 23 mm.) with much eroded shells. In my paper on “Marine Littoral Plant and Animal Communities,” published in Trans. N.Z. Inst., vol. 54, 1923, I have referred to this form as Notoacmea septiformis.

Distribution.—Tom Bowling Bay, Bay of Islands, Little Barrier Island, Taranga Island, Mount Maunganui, White Island, Stephen Island, Waipara, Taylor's Mistake.

(d.)

Subspecies subantarctica n. subsp.

Acmaea septiformis (not Q. & G.): Suter, Man. N.Z. Moll., p. 72, 1913. Acmaea helmsi (not Smith): Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924.

The above records from the Auckland and Campbell Islands probably refer to this subspecies.

Description of type from Campbell Island (in the Canterbury Museum): Shell thin, narrow-elliptical. apex in anterior fourth, posterior slope convex, anterior concave. Surface smooth, with fine low distant radiating lirae on posterior slope. Colour dark brown finely tessellated with lighter, inside uniformly dark shining bluish-black. Length, 11 mm.; breadth, 8 mm.; height, 4 mm.

Distribution.—Campbell Island; Auckland Island (as quoted above).

Notoacmea (Notoacmea) mayi May.

Acmaea cantharus (not Reeve): Tenson-Woods, Proc. Roy. Soc. Tas., 1877, p. 45, 1878. Notoacmea mayi May, Illus. Index Tasmanian Shells, p. 100, pl. 22, f. 3, 1923.

May named and figured but did not describe this species. No mention is made of a type specimen.

Shell ovoid, narrowing in front where it is obtusely pointed, depressed, the dorsal surface arched from apex to posterior border. Highest point in advance of centre. Apex at front margin or just above, and in advance of it when anterior slope is concave. The greatest distance observed between apex and anterior margin, in a shell 14 mm. in length, was 2 mm. Upper surface with concentric growth-lines only. Colour above creamy-white reticulated with dark-brown streaks of varying thickness Inside dark brown, lighter round spatula and along margin where it is cross-banded with yellow.

Largest specimen seen (from Frederic Henry Bay, Tasmania): Length, 19.5 mm.; breadth, 15 mm.; height, 5 mm.

Notoacmea mayi is allied to N. pileopsis of New Zealand, differing from the subspecies sturnus in possessing a marginal or submarginal apex, in being more depressed, in the anterior portion of the shell being more pointed, and generally in having more ground-colour on the upper surface.

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It is much smaller than the New Zealand form. It is perhaps a derivative of pileopsis, and might with propriety be regarded as one of the subspecies of that species.

Bionomics.—Occurs commonly in the upper portion of the intertidal belt on rocks. The apex and the greater portion of the upper surface are generally eroded. As in other species, a darkening of the inside colour corresponds with the eroded areas.

Distribution.—South-east Tasmania: Derwent Estuary and Frederic Henry Bay. Victoria: Port Fairy (Iredale).

Notoacmea (Notoacmea) septiformis (Q. & G.).

Notoacmea septiformis is an easily circumscribed species. It is very variable in coloration, but readily recognized by its form and sculpture. It is broadly elliptical, usually depressed, with apex in front fourth or sometimes in young shells quite near anterior margin. Posterior slope convex, anterior slightly concave. Shell quite thin with an acute margin. Upper surface with close very fine granulose radiating ribs, interspaces wider than ribs. In some cases ribs are obsolete. Prevailing colours outside are green and brown; some shells are entirely white. Usually the colours are tessellated, sometimes rayed. Inside is a bluish-white with a vaguely marked brown spatula and a rather broad margin, dark brown in dark shells and light brown or yellow with whitish rays in light-coloured shells.

Notoacmea septiformis is a close relation of N. pileopsis of New Zealand.

The radula was examined in specimens collected at Corny Point, South Australia. Centrals approximately long, narrow, with long projecting pointed cusps. Outer laterals smell. Teeth horn-colour with dark-brown cusps.

I find it difficult to define subspecies. Certain it is that great variation exists in shape and coloration, and the form from King George Sound appears at first sight different from the more elevated specimens from Victoria and Tasmania, but at Kangaroo Island a series proves that a depressed form may develop into a more elevated form. The same is witnessed in a series from Adventure Bay, Tasmania, though in the young the apex is more forward than it is in Western Australian examples. From comparisons such as these I concluded that a single variable species ranges along the coast of southern Australia and Tasmania. Dr. Lamy informs me that a Tasmanian specimen which I sent him is the same species as Quoy and Gaimard's type from Western Australia.

(a.)

Subspecies septiformis (Q. & G.).

Patelloida septiformis Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 362, pl. 71, f. 43, 44, 1834 (King George Sound, W. Aust.): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916: Desh. & M.-Edw. in Lam, Anim. s. Vert., 2nd ed., vol. 7, p. 550, 1836. Acmaea septiformis (Q. & G.): Pilsbry, Man. Conch., vol. 13, p. 55, pl. 37, f. 93, 94, 1891: Verco, Trans. Roy. Soc. S. Aust., vol. 36, pp. 184, 199, 1912.

The subspecies septiformis is characterized by the shell being comparatively thick, depressed, radiating lirae not well marked, sometimes obsolete, and by the colours in the young shells being predominantly light yellows and browns. The type figured by Quoy and Gaimard was black with brown radiating bands; inside bluish-white with black margin and brown spatula.

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Distribution.—Western Australia: King George Sound, Ellensbrook Yallingup. South Australia: Corny Point.

(b.)

Subspecies scabrilirata (Angas).

Acmaea septiformis (Q. & G.): Tenison-Woods, Proc. Roy. Soc. Tas., 1876, p. 50, 1877: Pritchard and Gatliff, Proc. Roy. Soc. Vic., vol. 15, p. 195, 1903: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 215, 1906. Acmaea scabrilirata Angas, Proc. Zool. Soc., 1865, p. 154 (Port Lincoln): Pilsbry, Man. Conch., vol. 13, p. 56, 1891. Tectura scabrilirata Angas, Proc. Zool. Soc., 1867, p. 220. Notoacmea flammea (not Q. & G.): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924 (including n. subsp. diminuta).

The distinguishing features of Angas's species are essentially those of N. septiformis. In no other Australian species of Patelloididae does the sculpture consist of “extremely slender riblets, each of which is surmounted by a series of minute granules.“

Mr. Tomlin informs me that the type specimen is very depressed. As it is only 12 mm. in length, it is probably a young shell.

The subspecies scabrilirata is distinguished by the thin shell with a ring of bluish-white callus within, with the highest point sometimes behind the apex, radiating lirae well marked, and by the colouring being often dark. Young shells are usually much depressed, but the adults are moderately elevated. The apex is relatively more advanced in young shells than in adult. The most elevated shell I have seen comes from Cape Schanck, Victoria: length; 12 mm.; height, 4.6 mm. The largest specimen examined was collected on King Island: length, 23 mm.; height, 6.5 mm.

Bionomics.—In the Derwent Estuary, Tasmania, this subspecies is found abundantly under stones just above low-tide mark. Like many other limpet-like species with delicate shells, it prefers smooth stones.

Distribution.—South Australia, Victoria, and Tasmania, on the coast generally. Kangaroo Island, King Island. New South Wales as far north as Sydney.

The validity of the two following species is doubtful.

Patelloida elongata Q. & G.

Patelloida elongata Q. & G., Voy. “Astrolabe,” Zool., vol. 3, p. 358, pl. 71, f. 12–14, 1834: Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 35, 1916. Acmaea elongata (Q. & G.): Pilsbry, Man. Conch., vol. 13, p. 59, pl. 37, f. 86, 87, 1891.

This species does not appear to have been collected since its discovery, nor is there anything in the description to separate if from the young of N. septiformis.

Acmaea subundulata Angas.

Acmaea subundulata Angas, Proc. Zool. Soc., 1865, p. 155 (Port Lincoln, S. Aust.). Tectura subundulata Angas, Proc. Zool. Soc., 1867, p. 220. Acmaea subundu-lata Angas: Pilsbry, Man. Conch., vol. 13, p. 57, 1891: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 214, 1906; vol. 36, pp. 185, 189, 1912. Patelloida subundulata (Angas): Hedley, Jour. Roy. Soc. W. Aust., vol. 1, p. 36, 1916: Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 236, 1924.

I know nothing of this species, and Iredale's note does not help to establish its validity. It has been recorded by Verco from several South Australian localities. The specimens were identified from Angas's “types,” but Iredale states that the three shells marked types belong to as many species. I suspect it to be a form of Notoacmea septiformis.

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Mr. J. R. Le B. Tomlin, to whom I applied for information on the type of subundulata, states that “there are two lots in the British Museum marked ‘type,’ a two and a one. The one is the real type. Anterior slope steep. Interior bluish-white except the margin, which is narrowly and sharply coloured light brown with about 30 regular dark flecks; spatula well defined. No ribs outside; the shell is practically smooth. Outside it is a sort of mottled yellowish.”

Notoacmea (Notoacmea) petterdi (Tenison-Woods). (Text-fig. E.)

Acmaea petterdi Tenison-Woods, Proc. Roy. Soc. Tas., 1876, p. 155, 1877 (north-west coast of Tasmania: type in Tasmanian Museum): Pilsbry, Man. Conch., vol. 13, p. 54, 1891. Notoacmea petterdi (Tenison-Woods): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 235, 1924. Tectura septiformis (not Q. & G.): Angas, Proc. Zool. Soc., p. 220, 1867.

Specimens from Sydney have, through the kindness of Mr. Clive Lord, been compared with the type.

Description of specimens from Coogee, New South Wales: Shell broadly elliptical, moderately high, posterior slope arched, anterior also slightly convex, very steep. Apex in anterior fourth, sharp-pointed. Surface ornamented with about 28 fine radiating threads extending from apex to margin, interspaces several times broader than the ribs, smooth, with concentive growth-lines. Colour creamy white with about 40 light-brown radiating bands. Inside smooth, shining; the spatula brown, dark and light blotchy, ill-defined; surrounding the spatula it is bluish-white; margin broad, yellowish-brown banded with dark brown. Length, 24 mm,; breadth, 21.5 mm.; height, 9.5 mm.

In young shells the inside coloration, especially of exposed eroded specimens, is usually fairly dark, sometimes there being none of the bluish-white present; the outside also may be of a uniform brown colour except where erosion makes it a lighter shade. In half-grown shells there is often a good deal of brown inside with only a narrow band of bluish-white developed around the spatula. The bluish-white colour is always present in adult shells, and is accompanied by a thickening of the shell. The margin, however, always remains thin and sharp.

Radula of specimen from Port Jackson: Centrals with long bases, approximating towards the anterior end, and with long pointed brown cusps pointing directly outwards. Inner laterals small with triangular pointed brown cusps pointing towards outer edge of ribbon. Outer laterals short with broad brown obtuse cusps pointing towards centre.

Notoacmea petterdi bears a superficial resemblance to N. pileopsis of New Zealand, especially in its inside coloration. In shape and sculpture, however, it is quite different, and easily distinguished from every other Australian or New Zealand species.

Bionomics.—Notoacmea petterdi is abundant on rocks between tide-marks on the coast in the vicinity of Sydney. Small individuals occur in the barnacle association about half-tide, but the largest occur in the Cellana belt above this. These shells are often much eroded. Near high-tide mark in sheltered spots small well-preserved light-coloured shells occur with Siphonaria and Tectarius.

Distribution.—Tasmania: North-west coast. Victoria: Port Phillip, Mallacoota. New South Wales: Port Jackson, Newcastle. Queensland: Caloundra.

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Subgenus Parvacmea Iredale.

Parvacmea (subg. of Notoacmea) Iredale, Trans. N.Z. Inst., vol. 47, p. 428, 1915 (type: Acmaea daedala Suter).

Small shells, translucent, with usually a shelly deposit within. Apex forward, anterior slope concave, posterior convex. Closely related to the subgenus Notoacmea, differing mainly in size and in the texture of the shell.

Notoacmea (Parvacmea) daedala (Suter).

Acmaea flammea (not Q. & G.): Hutton, Trans. N.Z. Inst., vol. 15, p. 132, 1883; Proc. Linn. Soc. N.S.W., vol. 9, p. 373, 1884. Acmaea daedala Suter, Proc. Mal. Soc., vol. 7, p. 328, pl. 27, f. 30–32, 1907 (Auckland Harbour; type in Canterbury Museum); Man. N.Z. Moll., p. 67, pl. 5, f. 11, 1913: Iredale, Trans. N.Z. Inst., vol. 40, p. 379, 1908: Bucknill, Sea-shells N.Z., p. 11, pl. 5, f. 9, 1924.

A small species with a thin shell which cannot be confused with any other species. It is allied to N. septiformis. The shell is elliptical, but the proportion of length to breadth varies, some shells being narrower than others. Posterior slope convex, anterior concave. Apex at about anterior fourth. There are microscopic radiating striae. Colour distinctive being greenish-yellow with light-brown radiating and anastomosing lines. The depth of colour varies. The interior may be the same, or there may be a bluish-white callus except at margin, which is brown-and yellow-rayed. The callus increases in thickness with age. It begins as a ring between spatula and margin. The radula-teeth are quite similar to those of Notoacmea pileopsis and N. septiformis, the centrals being long with the cusps projecting and the inner laterals being larger than the outer.

Bionomics.—Plentiful along the coast under stones between tides, usually in sheltered situations, as rock-pools. It is gregarious.

Distribution.—Mangonui, Hauraki Gulf, Mount Maunganui, Gisborne, Cook Strait, Picton, Greymouth, Waipara, Banks Peninsula, Shag Point, Otago Peninsula.

Notoacmea (Parvacmea) subtilis (Suter).

Acmaea daedala Suter var. subtilis Suter, Proc. Mal. Soc., vol. 7, p. 324, pl. 27, f. 33, 1907 (between Little Barrier Island and Tiritiri, in 20 fathoms; type in Wanganui Museum); Man. N.Z. Moll., p. 68, pl. 5, f. 12, 1913.

Shell fragile and transparent, whitish with radiate narrow brown lines. This is apparently a deep-water form with the usual characteristics of a thin and light-coloured shell.

Distribution.—Hauraki Gulf, 10–20 fathoms (Suter); Awanui Bay, 12 fathoms.

Notoacmea (Parvacmea) nukumaruensis n. sp. (Plate 99, fig. 3.)

Description of type specimen (in Mr. H. J. Finlay's collection): Shell small, opaque, base elliptical, apex about anterior fourth, anterior slope straight, posterior slope falling away at first gradually then steeper towards margin. In region of apex the outer layer of shell is missing, elsewhere it is smooth except for concentric growth-lines. Shell white with about 25 radiating brown bands on lower portion. On posterior slope a few of these bands anastomose. Length, 4 mm.; breadth, 3 mm.; height, 2 mm.

Locality.—Nukumaru, north of Wanganui, in beds of Pliocene age. Besides the type specimen, two smaller shells were collected.

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Notoacmea nukumaruensis is closely allied to N. daedala and N. subtilis. Possibly it is the species recorded from the Pliocene of Wanganui and Petane by Hutton under the name of Acmaea flammea (Macleay Mem. Vol., p. 73, 1893).

Notoacmea (Parvacmea) helmsi (Smith). (Text-fig. F.)

Acmaea helmsi Smith, Proc. Mal. Soc., vol. 1, p. 58, pl. 7, f. 4, 5, 1894 (Greymouth; type in British Museum): Suter, Proc. Mal. Soc., vol. 7, p. 324, 1907; Man, N.Z. Moll., p. 69, pl. 7, f. 3, 1913: Bucknill, Sea-shells N.Z., p. 12, pl. 5, f. 8, 1924. Notoacmea helmsi (Smith): Iredale, Trans. N.Z. Inst., vol. 47, p. 428, 1915. Acmaea parviconoidea Suter var. leucoma Suter, Proc. Mal. Soc., vol. 7, p. 322, 1907 (Heathcote Estuary; type in Wanganui Museum); Man. N.Z. Moll., p. 70, 1913. Acmaea scapha Suter, Proc. Mal. Soc., vol. 7, p. 324, pl. 27, f. 34, 35, 1907 (Dunedin; type in Wanganui Museum); Man N.Z. Moll., p. 72, pl. 5, f. 15, 1913. Acmaea septiformis (not Q. & G.): Suter, Man. N.Z. Moll., p. 72, 1913 (in part; Suter's septiformis is a mixture of three species).

Notoacmea helmsi is a small species with a thin conical shell. Base broadly elliptical, almost orbicular, to narrow-oblong. Shell may be elevated or moderately depressed; apex subcentral or about anterior fourth. Upper surface dull, smooth. Margin sharp, interior shining. Outside of most ornamental specimens is greenish-brown with 30 to 40 radiating dark lines. Inside spatula is brown with a lighter centre; muscle-scar greenish with dark border; outside this is a broad greenish-white band; margin dark brown with light spots along edge. Lighter specimens are found. In some the outside is creamy white but inside is marked like the normal specimens, only paler; in others the outside is yellowish-white and the inside greenish-white surrounded by white with the margin yellow. On these light-coloured specimens was founded Suter's variety leucoma. They are, however, merely colour-variants of no taxonomic value. Very young specimens have the shell entirely brown. Apparently the colour-bands are not developed until the shell is 2–3 mm. in length.

The outline of base of shell is very variable. A shell from Heathcote Estuary is 10.8 × 9.8 mm. Two shells from Tauranga are 6.3 × 4.7 mm. and 5.6 × 3.3 mm. respectively. In this last specimen the sides are parallel. The type of Acmaea scapha is a young shell with parallel sides, and without the colour-rays developed. It differs only from the ordinary young ones in having the sides straight instead of curved.

Radula of specimen from Wellington Harbour: Centrals long with short recurved cusps, approximating towards the tips. Laterals in two pairs near the centre of the dental ribbon, short with small cusps.

Bionomics.—Notoacmea helmsi is found on stones, shells, Zostera leaves, and other objects on mud-flats between tide-marks in harbours and estuaries. Like all shells found in such situations, the apex and sometimes almost the whole of the outer surface are eroded. The narrow shells are probably epharmonic variations associated with life on stems of algae and leaves of Zostera. I have recorded Notoacmea scapha growing on Zostera leaves in Tauranga Harbour (Trans. N.Z. Inst., vol. 44, p. 543, 1923). These shells were narrow but with sides not quite so straight as the type of Acmaea scapha with which they were compared. Narrow forms of Acmaea growing on Zostera and algae have been recorded for northern species: thus Pilsbry (Man. Conch., vol. 13, 1891) mentions A. depicta and A. triangularis.

Picture icon

Fig. 1.—Chiazacmea heteromorpha Oliver.
Fig. 2—Notoacmea pileopsis cellanoides Oliver.
Fig. 3.—N. nukumaruensis Oliver.
Fig. 4.—N. virescens Oliver.
Fig. 5.—N. corrosa Oliver.
Fig. 6.—N. alta Oliver.
Fig. 7.—N. badia Oliver.
Fig. 8.—N. scopulina Oliver.

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Distribution.—Doubtless Bay; Auckland, Tauranga, Wellington, Lyttel-ton, and Otago Harbours; Heathcote Estuary; Porirua Harbour, Blind Bay (Suter); Picton (Bucknill).

Notoacmea (Parvacmea) virescens n. sp. (Plate 99, fig. 4.)

Description of type specimen from Kekerangu (type in Dominion Museum): Shell depressed, apex anterior, anterior slope slightly concave, posterior slope slightly convex, smooth. Brownish-black with 32 radiating bluish-grey lines, several of them not reaching the margin. Interior greenish-white, the margin dark brown, banded along extreme edge with yellow rays. Anterior end of spatula pale green; an irregular brown blotch at apex (probably due to external erosion). Region outside muscle-scar slightly calloused. Length, 8.5 mm.; breadth, 7 mm.; height, 3 mm.

Range of variation: In young shells the colour-pattern of the apical region is best developed, and is then seen to consist of regularly anastomosing reddish-brown lines, radiate in the marginal region. The lighter rays are often distinctly greenish. In young shells all the light rays reach the margin, in adult shells many do not. The general colour darkens as the shell grows.

N. virescens is allied to N. helmsi, but differs in its smaller size, narrower outline, and narrower and more regular colour-bands reaching to the apex in young shells. It also approaches N. daedala, but is a larger, heavier shell, with different coloration.

Bionomics.—Living on intertidal rocks on the coast.

Distribution.—New Zealand: Kekerangu, on grey marls; Timaru.

Subgenus Conacmea n. subg.

Small shells, conoidal or conical, generally elevated with all slopes more or less convex. No internal porcellaneous layer. Type: Acmaea parvi-conoidea Suter.

Notoacmea (Conacmea) parviconoidea (Suter).

Acmaea conoidea (not Q. & G.): Hutton, Trans. N.Z. Inst., vol. 15, pp. 127, 132, pl. 15, f. K, 1883; Proc. Linn. Soc. N.S.W., vol. 9, p. 373, 1884. Acmaea parviconoidea Suter, Proc. Mal. Soc., vol. 7, p. 321, pl. 27, f. 22–25, 1907 (Sumner; type in Canterbury Museum): Iredale, Trans. N.Z. Inst., vol. 40, p. 378, 1908: Suter, Man. N.Z. Moll., p. 69, pl. 5, f. 13, 1913: Bucknill, Sea-shells N.Z., p. 12, pl. 5, f. 4, 1924. Acmaea parviconoidea Suter var. nigrostella Suter, Proc. Mal. Soc., vol. 7, p. 322, pl. 27, f. 26–29, 1907 (Titahi Bay; type in Wanganui Museum); Man. N.Z. Moll., p. 70, pl. 5, f. 14, 1913.

In reviewing the New Zealand Acmaeidae, Suter (Proc. Mal. Soc., vol. 7, p. 322) pointed out that the New Zealand species was distinct from the Australian one described by Quoy and Gaimard as Patelloida conoidea, but at the same time he stated that he had specimens from Tasmania corresponding exactly with A. parviconoidea. The position was thus left in a confused state.

Notoacmea parviconoidea occurs in two rather distinct growth-stages. What I regard as the normal adult form of the species has apex about anterior third, anterior slope straight below but with apex advancing a little above, and posterior slope very slightly convex. It is generally a light-coloured shell with dark-brown radiating bands. In some shells these form a stellate pattern of fewer rays, often with a purplish tinge, in the apical portion of the shell. Young shells showing the coloured radiating

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rays correspond with Suter's variety nigrostella, but are in my opinion merely colour variations of no taxonomic importance. Nigrostella, however, is the only name that has been applied to the ordinary form of the shell. The other growth-stage has both posterior and anterior slopes convex, posterior more so than anterior, and apex advances a little in front of curve of anterior slope. The colour of this form is usually a uniform black, or there may be a few light radiating bands. The type of Suter's parviconoidea belongs to this dark-coloured stage.

The relationship between these forms can be observed in good series from almost any locality. The dark (parviconoidea) is the young state. In certain situations, as on shells of Mytilus, it persists in this form throughout life, but on rocks it usually quickly changes to the light-coloured (nigrostella) form. Sometimes the change is very abrupt, and a dark convex form appears seated on a light straight-sided shell. Such shells are frequent on the piles of the pier at New Brighton, and it was through these that the relationship of the two forms was discovered.

Most of the shells included by Suter in his nigrostella are bleached specimens, white with traces of the stellate pattern remaining. In this state they look so distinct that they were not recognized as being the young of the ordinary rock form.

The radula has the centrals long with projecting pointed cusps. The inner laterals are shorter than the centrals but the cusps project in a similar way. The outer laterals are small.

Bionomics.—Notoacmea parviconoidea occurs abundantly throughout New Zealand in the intertidal belt, being especially common in the upper half. It is found in the most exposed situations and also within the shelter of harbours. On the shells of Mytilus planulatus and Modiolus pulex it occurs in the dark (parviconoidea) form. A proportion of the shells have light colour-bands, which, however, are generally absent on the posterior section of the shell. On rock-surfaces the shells are generally of the light-coloured, or nigrostella, type with the apical portion much eroded. In this state they are almost indistinguishable from shells of Notoacmea scopulina. The animals, however, are easily recognized, that of scopulina being yellow, while parviconoidea is nearly white.

Distribution.—New Zealand: from Maunganui Bluff and Doubtless Bay southwards to Greymouth and Otago Peninsula; Little Barrier Island, Great Barrier Island; Chatham Island (Suter).

Notoacmea (Conacmea) corrosa n. sp. (Plate 99, fig. 5, and text-fig. G.)

Acmaea conoidea (not Q. & G.): Tension-Woods, Proc. Roy. Soc. Tas., 1877, p. 45, 1878: May, Check-list Moll. Tas., p. 46, pl. 22, f. 4, 1921.

Description of type specimen: Shell conical, high, apex subcentral, anterior and posterior slopes convex, thin, margin sharp. With the exception of a narrow strip along margin the whole of exterior is eroded. Where not eroded surface is smooth but dull. Colour of eroded surface blotchy greyish and brown; of uneroded, brownish-black. Interior brownish, muscular impression lighter, margin jet-black. Contour of base elliptical, slightly narrowed in front, and with straight sides. Length, 8.5 mm.; breadth, 6.5 mm.; height, 5 mm. Type collected at Blackmans Bay, Derwent Estuary, Tasmania, and deposited in the Dominion Museum, Wellington.

Variations from type: There is little variation in the shape of the shell. Some are a little broader in proportion to length and some are more

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elevated than others. Uncorroded apices are only to be found in very young specimens. The outside is sometimes marked by a few radiating light bands, usually a broad one at each outer posterior angle, and others may be present. The interior is usually darker than in the type; often it is entirely black except for the muscular impression, which is whitish. Light colour-bands on the outside show on the inside as yellowish bands at the margin.

Radula: Centrals approximate, long, with long pointed recurved cusps. Inner laterals as wide as the centrals and with long pointed cusps. Outer laterals small with pointed cusps.

Bionomics.—In the Derwent Estuary Notoacmea corrosa lives on rocks from about half-tide to high-tide mark. It is found in the Mytilus planulatus association and in the association of small-shelled animals above it. Like all shelled animals regularly exposed to the atmosphere, the exterior of the shell is more or less eroded. In adult specimens there is only a narrow margin of uneroded surface.

Distribution.—Tasmania.

Notoacmea (Conacmea) alta n. sp. (Plate 99, fig. 6.)

Acmaea conoidea (not Q. & G.): Pritchard and Gatliff, Proc. Roy. Soc. Vic., vol. 15, p. 195, 1903: Verco, Trans. Roy. Soc. S. Aust., vol. 30, p. 214, 1906.

Description of type specimen from South Australia (in Dominion Museum): Shell conical, elevated, apex subcentral, acute, anterior slope nearly straight, posterior slope regularly arched. Margin sharp, plane of base arched. Shell smooth, with concentric growth-lines. Black with 18 pale-green bands radiating from apex; colour-bands show in interior. Length, 6 mm.; breadth, 5 mm.; height, 4 mm.

In radula centrals have long bases and long pointed projecting cusps, inner laterals have large blunt cusps and outer laterals are small.

Distribution.—South Australia: Port Macdonnell (Verco). Victoria: Barwon Heads, Port Phillip, Cape Otway (Pritchard and Gatliff).

The only specimen of this species that I have seen was sent by Mr. C. J. Gabriel, with the locality “South Australia.” In its elevated form and radiate colour-bands it bears some resemblance to Quoy and Gaimard's Patelloida conoidea, hence I quote the above references and localities as referring to it. It recalls the juvenile form N. parviconoidea found on Mytilus shells.

Subgenus Thalassacmea n. subg.

Shell thin, depressed, orbicular, apex central. Colour uniformly dark. Inner lateral teeth very broad. Type: Notoacmea badia Oliver.

Notoacmea (Thalassacmea) badia n. sp. (Plate 99, fig. 7; and text-fig. H.)

Description of type specimen: Collected at St. Clair, Dunedin, in rock-pool between tide-marks. Type in Dominion Museum, Wellington. Shell broadly elliptical, depressed, apex about anterior fourth, posterior slope convex, steep towards margin, anterior slope convex, steep. Apical portion eroded, lower portion slightly roughened. Eroded portion light-coloured, remainder purplish-brown, inside shining, dark brown, region of spatula lighter but varigated with darker markings corresponding with eroded areas outside. Length, 10.5 mm.; breadth, 9 mm.; height, 3.5 mm.

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All the shells collected are uniform in shape and colour with the type. The species resembles N. helmsi, but is more depressed and bears no radiating colour-bands. The radula, however, is quite different. The centrals approximate at base, cusps blunt-pointed, inner edges straighter than outer, horn-colour with black edges. Inner laterals as broad as high, round at ends, distance between base about half width of base of a tooth, horn-colour with black margin. Outer laterals very small, blunt-pointed, horn-colour with blackish tip.

Bionomics.—Found only in rock-pools low down in the intertidal belt, where it is fairly common. The greater portion of the outside of the shell is eroded.

Distribution.—St Clair, Dunedin.

Subgenus Subacmea n. subg.

Shell conical, apex forward, regularly ribbed. Generally light-coloured with dark rays. Teeth nearly uniform in size with the inner laterals in advance of the outer. Type: Notoacmea scopulina Oliver.

Notoacmea (Subacmea) scopulina n. sp. (Plate 99, fig. 8; and text-fig. I.)

Acmaea septiformis (not Q. & G.): Bucknill, Sea-shells N.Z., p. 13, pl. 5, f. 3, 1924.

Description of type specimen: Shell somewhat depressed, apex at anterior third, posterior and anterior slopes convex. Base ovoid-elliptical, sides tapering towards anterior end which is narrower. About 30 low radiating ribs. Colour of ribs white, interspaces black. Interior smooth and shining, bluish-white faintly rayed with dark lines corresponding to interspaces between ribs. A few dark-brown blotches near apex corresponding with eroded portions on outside. Margin striped with dark brown and white. Length, 15 mm.; breadth, 12 mm.; height, 4.5 mm. Type from Motutara, west coast of Auckland (in the Dominion Museum).

Variations from type (Motutara specimens): Shape of shell fairly constant. Smaller shells narrow-elliptical, larger ones regularly elliptical (that is, not narrowing much in front). A few specimens are moderately elevated. In the larger specimens ribs increase by interpolation to about 40. There is considerable variation in the coloration of the interior. A bluish-white tinge is evident in most specimens. Dark-brown blotches are few or many according to the amount of erosion on outside. There is usually a dark-brown or blackish band within margin, which always shows alternate black and white rays. A characteristic feature are white radiating rays on darker bluish background. Largest specimen—length, 19 mm.; breadth, 15 mm.; height, 5 mm.

Specimens similar to those from Motutara come from Charleston, on the west coast of the South Island.

I have associated with the Motutara specimens in the present species a form common on intertidal rocks at Lyall Bay and St. Clair. They have about 25 ribs showing only at margin, the remainder of surface being eroded. Interior bluish or brownish white with dark blotches corresponding to eroded areas on outside. There is a submarginal dark band, outside which are the alternating black and white rays of margin. Length, 10–12 mm. These specimens present an appearance somewhat different from the majority of the Motutara specimens, but this is apparently due to the difference of habitat, and to the fact that the Motutara specimens are for the most part covered with Melobesia. Clean eroded specimens from both localities closely resemble one another, and appear to me to be conspecific.

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The radula of the Motutara specimens has two broad short centrals approximating in the middle line and with broad recurved cusps. The laterals, of which there are two pairs, the posterior slightly more divergent than the anterior, which are separated by a distance equal to about half the width of the cusps, have broad cusps. All the teeth are thus of approximately the same size.

Bionomics.—Mr. A. W. B. Powell, who collected the Motutara specimens, describes the habitat as “on perpendicular rock, high up but exposed to the fullest force of the waves at high water.” Most of the shells are covered with Melobesia, which protects them from erosion. When clean they are deeply eroded over the upper half.

At Lyall Bay Notoacmea scopulina is found associated with N. parviconoidea on rocks in the Porphyra and Chamaesipho associations in the mid-tide belt. They are clean, but deeply eroded except near margin.

Distribution.—New Zealand: Motutara, Charleston, Lyall Bay, St. Clair.

Bucknill records A. septiformis from Chicken Island, Dunedin, Auckland and Campbell Islands.

Notoacmea corrodenda (May).

Patelloida corrodenda May, Proc. Roy. Soc. Tas., 1919, p. 66, pl. 17, f. 24, 1920 (Frederic Henry Bay, Tasmania).

Notoacmea corrodenda is distinguished by its rather depressed form, with apex in anterior third, and the numerous (20 to 40) low radiating ribs. Apex usually eroded. Ribs white, and interspaces between them at margin black. In interior spatula is brown with white border. Outside the muscle-impression is a light-or dark-brown band, margin banded black and white, the white corresponding to ribs. Radula has centrals with long bases and long projecting sharp-pointed cusps. The inner laterals have short bases and projecting pointed cusps shorter than the centrals. The outer laterals are small. The radula is thus essentially similar to that of Notoacmea pileopsis.

Notoacmea corrodenda is closely related to the New Zealand species N. scopulina, differing principally in coloration, the white margined spatula being especially characteristic of corrodenda.

Bionomics.—Notoacmea corrodenda is common in the Derwent Estuary, living with N. corrosa and Chiazacmea flammea on intertidal rocks. It is found in the Mytilus planulatus association and the open rock-association above it. The exterior is generally eroded over more than half the surface. May records this species on rocks about half-tide mark, associated with Siphonaria diemenensis.

Distribution.—South-east Tasmania.

Atalacmea Iredale.

Atalacmea Iredale, Trans. N.Z. Inst., vol. 47, p. 427, 1915. Type: Patella fragilis Sowerby.

This genus includes but a single species, and is an extreme form, apparently developed in response to the particular conditions under which it lives. The shell is much depressed, being nearly flat, broadly elliptical, truncate in front, apex near anterior margin and directed forwards.

The radula-teeth resemble those of Notoacmea pileopsis. The centrals are long with long projecting sharp-pointed cusps. The inner laterals

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have shorter bases but similar long sharp-pointed projecting cusps. Outer laterals small.

Atalacmea is apparently an offshoot of Notoacmea, and is distinguished by its extraordinary shell.

Atalacmea fragilis (Sowerby).

Patella fragilis Chemnitz, * Conch. Cab., vol. 11, f. 1921, 1290: Sowerby, Genera Shells, Patella, pl. 140, f. 6, 1823. Patella unguis-almae Lesson, Voy. “Coquille,” Zool., vol. 2, p. 420, 1830. Acmaea unguis almae (Lesson): Odhner, Vid. Medd. Dansk. Nat. For., Bd. 77, p. 10, 1924. Patella solandri Colenso, Tas. Jour. Sci., vol. 2, p. 226, 1844 (Tokomaru); Trans. N.Z. Inst., vol. 14, p. 168, 1882. Patelloida fragilis (Chemnitz): Q. & G., Voy. “Astrolabe.” Zool., vol. 3, p. 351, pl. 71, f. 28–30, 1834: Desh. & Edw., Lam. Anim. s. Vert., ed. 2, vol. 7. p. 552, 1836. Tectura fragilis (Chemnitz): Hutton, Cat. Mar. Moll. N.Z., p. 43, 1873: von Martens, Crit. List Moll. N.Z., p. 35, 1873. Acmaea fragilis (Chemnitz): Hutton, Man. N.Z. Moll., p. 88, 1880; Proc. Linn. Soc. N.S.W., vol. 9, p. 374, 1884: Pilsbry, Man. Conch., vol. 13, p. 59, pl. 37, f. 14, 15, 1891: Suter, Proc. Mal. Soc., vol. 7, p. 317, pl. 27, f. 11 (dentition), 1907; Man. N.Z. Moll., p. 68, p. 7, f. 2, 1913: Bucknill Sea-shells N.Z., p. 12, pl. 5, f. 5, 1924. Atalacmea fragilis (Sowerby): Iredale, Proc. Linn. Soc. N.S.W., vol. 49, p. 238, 1924.

In the extremely depressed almost flat form this species is quite unlike any other. I have found no variation in the species. Outside, shell is whitish concentrically banded with light brown; inside there is a broad concentric green band and a green patch down centre, but the shell being translucent the green is visible from above and dominates colour of exterior.

Bionomics.—This species occurs under stones between tide-marks, usually nearer low-tide mark. It almost invariably affects smooth stones, and when disturbed moves off at a fair speed. It is a gregarious species. The shells are always clean.

Distribution.—Tom Bowling Bay, Little Barrier Island, Taranga Island, Whangarei Heads, Hauraki Gulf, Slipper Island, Tauranga, Maria Peninsula, Cook Strait, Banks Peninsula, Shag Point, Tokomaru (Colenso), Chatham Islands (Suter), Stewart Island.

Acknowledgments.

It would have been impossible to write the foregoing account without the assistance of many who have willingly and often at much trouble gathered for me the specimens I required. I have also received specimens, including types, on loan, and have obtained information from persons to whom types were accessible. Therefore, for much help freely given, I wish to express my sincere thanks to the following: Messrs. E. Ashby, Blackwood, South Australia; C. Barrett, Melbourne; A. E. Brookes, Matamata; H. J. Finlay, Dunedin; C. J. Gabriel, Melbourne; H. Hamilton, Wellington; Dr. E. Lamy, Paris; Messrs. C. Lord, Hobart; W. L. May, Sandford, Tasmania; Miss M. K. Mestayer, Wellington; Messrs. H. S. Mort, Sydney; A. W. B. Powell, Auckland; Professor R. Speight, Christchurch; Dr. J. Allan Thomson, Wellington; Mr. J. R. le B. Tomlin, St. Leonards-on-Sea, England; Mr. C. Walton, Adelaide. I also desire to thank Miss E. Richardson for assistance in preparing the illustrations.

[Footnote] * This name is rejected because Chemnitz was not a binomialist, though binomials are the rule in the volume in which it was described.