not Cirrhigaleus Tanaka, 1912 which Fowler (1941, p. 262) recognises as a subgenus of Squalus.

The genus is cosmopolitan and many regional species have been described, though the majority of these, like the Australasian examples, are now regarded as synonyms. The number of valid species is not yet definitely known, but four are recognisable on present information. These are, Squalus acanthias Linnaeus, 1758, S. blainvillii (Risso, 1826), S. megalops (Macleay, 1882), and S. cubensis Rivero, 1936. Decision on the status of other named species, particularly those from the southern hemisphere and the Indo-Pacific, must await critical comparison of material, though as Bigelow & Schroeder (1948, 1957) have shown it is possible to arrange them in three species groups having facies corresponding to those of S. acanthias, S. blainvillii and S. megalops-cubensis respectively. Present indications are that all named species of Squalus will fit into the above four species.

Diagnoses of the three species groups are as follows, adapted slightly from Bigelow & Schroeder (1957, p. 27), and illustrated in Text-fig. 1.

(a) S. acanthias group, the members of which generally have white spots along the upper half of the trunk, though in large specimens the spots may be faint or absent; the inner (posterior) corner of the pectoral fin rounded, the distal margin moderately concave; the 1st dorsal spine over or behind the inner corner of the pectoral, such that the distance from origin of exposed spine to 5th gill-opening is at least as long as the distance from anterior edge of eye to 5th gill-opening; the midpoint of pelvic base about midway between perpendiculars at posterior free tip of 1st dorsal fin and exposed origin of 2nd dorsal spine; the anterior nasal flap simple, triangular.

(b) S. blainvillii group, with uniform coloured members, not spotted at any stage of growth; the inner pectoral corner and distal pectoral margin as in S. acanthias group; the 1st dorsal spine over or anterior to the inner pectoral corner, such that the distance from origin of exposed spine to 5th gill-opening is not more than the distance from anterior edge of eye to 2nd gill-opening; the midpoint of pelvic base generally nearer to a perpendicular at posterior free tip of 1st dorsal fin than to one at exposed origin of 2nd dorsal spine, the anterior nasal flap complex, bilobed.

(c) S. megalops-cubensis group with members similar to those of S. blainvillii group in colour, relative positions of fins and shape of nasal flap, but differing in having the inner pectoral corner pointed, the distal pectoral margin deeply concave, and in the dermal denticles.

It should be noted that group (b), named here S. blainvillii, is named S. fernandinus in Bigelow & Schroeder (1957, p. 29), who like the other authors they refer to, regard S. blainvillii as a synonym of S. fernandinus. There is no doubt that S. blainvillii and S. fernandinus as recognised by Bigelow & Schroeder are the same species—i.e., uniform coloured forms with characters as outlined above. The use of the name S. fernandinus for these forms is of fairly long standing, dating back at least to Garman (1913, p. 195). It has been followed also by Lahille (1928, p. 326), by Fowler (1941, p. 261), by Bigelow & Schroeder (1948, p. 478), by Smith (1950, p. 60), by Bigelow, Schroeder & Springer (1953, p. 220) and many others. The New Zealand representative of the group was suggested as S. fernandinus by Richardson & Garrick (1953, p. 36). This usage is erroneous. The original account of S. fernandinus by Molina (1782, p. 229), based on material from Juan Fernandez off Chile, is not readily available, but Dr. D. E. Tucker, of the British Museum has kindly supplied me with a transcript of it. The relevant descriptive portion is as follows:

“Il Tollo, Squalus fernandinus^* è una specie di Pesce cane, un poco più grande del pesce gallo, rimarchevole per due spine, che ha sul dorso, come lo Squalus

acanthias, le qualí sono triangolari, ricurvate verso la punta, dure come l'avorio, lunghe due pollici e mezzo, e larghe in ciascuno de' lati da cinque linee.

The brief diagnosis at the end of the account, describing the body as being spotted leaves no doubt that Molina's material belongs to the S. acanthias group, for in the S. blainvillii group and the S. megalops-cubensis group there are no spots on the body at any stage of growth. The only disturbing feature in this interpretation is the dorsal spine size quoted by Molina—viz., two and a-half inches long and five lines wide. Spines of these dimensions would denote an abnormally large specimen of S. acanthias, but could be more readily attributed to the heavy-spined S. blainvillii. However, I do not regard this as a decisive factor compared with the diagnosis of the body being spotted.

Mr. W. C. Schroeder, of Woods Hole Oceanographic Institution, informs me that he and Dr. H. B. Bigelow have seen only a French version of Molina's account, published in 1789, which unfortunately omitted the diagnosis given in the originial. This suggests a possible source for other misinterpretations of the affinities of S. fernandinus. Whatever the reason, there has been considerable confusion in the literature, since some authors and particularly Jordan & Evermann (1896, p. 54), Regan (1908, p. 46), Norman (1937, p. 9) and various others following Regan and Norman correctly attributed S. fernandinus to the S. acanthias group. As is shown in the section below dealing with Australasian members of the S. acanthias group, there is little cause for believing that S. fernandinus is even specifically distinct from S. acanthias, though final decision on this must await critical comparison of material from southern South America, the type locality of S. fernandinus.

The two New Zealand species of Squalus fall into the S. acanthias and S. blainvillii groups respectively. Compared with North Atlantic specimens of about equal size, I cannot separate my material from the species S. acanthias and S. blainvillii. The Australian fauna similarly includes S. acanthias and S. blainvillii, as well as a third species, S. megalops, the last representing the S. megalops-cubensis group.

As the material available for this study covers a fairly extensive size-range, it provides an opportunity for examining the affect of growth on those features currently used for diagnosing Squalus species. In this respect I find that the dimensional feature most affected by growth is that of the position of the pelvic fin relative to the dorsal fins. In S. acanthias the pelvic fin is relatively further rearward than it is in S. blainvillii, S. megalops or S. cubensis. Various means of expressing this difference have been put forward, but not all of these have been successful (for an example see Bigelow & Schroeder, 1948, p. 453; 1957, p. 27). Some at least of the reasons for the difficulties encountered can be seen in Text-fig. 2 where eight New Zealand specimens of S. acanthias and six of S. blainvillii are compared. It can be noted that juveniles of both species have similar proportions, the pelvic fin being much nearer to the 1st dorsal than to the 2nd dorsal. Both species undergo growth change of a similar nature, the pelvic to 1st dorsal region growing at a faster rate than the pelvic to 2nd dorsal region. At the same time the interspace between the 1st and 2nd dorsal fins comes to occupy a proportionately greater percentage of the total length. The difference between the species appears to lie in a faster prepelvic growth rate in S. acanthias, with the result that middle-sized specimens of S. acanthias have the pelvic fin only slightly nearer to the 1st dorsal than to the 2nd, while in S. blainvillii this condition does not occur until adult size is reached. Further growth of S. acanthias—i.e., from middle to adult size, results in the pelvic fin coming to lie about midway between the 1st and 2nd dorsals and thus increases the difference between the two species since this more posterior position of the pelvic is not attained by S. blainvillii. From this it is obvious that any expression of the position of the pelvic fin relative to the dorsals will need qualification to cover at least small and large specimens. In this respect.

the following is suggested as a preliminary step until sufficient data are available to allow more accurate diagnoses to be made.

(a) S. acanthias: midpoint of pelvic base nearer to a perpendicular at posterior tip of 1st dorsal than to one at exposed origin of 2nd dorsal spine in juveniles and half-grown specimens, but about midway between these levels in larger specimens.

(b) S. blainvillii (and also S. megalops-cubensis): midpoint of pelvic base always nearer to a perpendicular at posterior tip of 1st dorsal than to one at exposed origin of 2nd dorsal spine.

The position of the 1st dorsal spine relative to the inner (posterior) corner of the adpressed pectoral differs strongly between S. acanthias and S. blainvillii when

specimens of equal size are compared (Text-fig. 1), but again because of growth change there is overlap in this feature when complete size-ranges are examined. Thus juveniles of S. blainvillii have the 1st dorsal spine about midway between the levels of the axil and inner corner of the pectoral, while in adults it is further rearward, about over the inner corner. In S. acanthias the spine is over the inner corner in juveniles, but well behind this level in adults. This more rearward position of the 1st dorsal spine in S. acanthias has been made use of recently by Bigelow & Schroeder (1957, p. 27), who, in characterising their species-groups, find that the distance from spine to 5th gill-opening is not less than the distance from the anterior edge of eye to 5th gill-opening in S. acanthias, but not more than that to the 2nd gill-opening in S. blainvillii, S. megalops and S. cubensis. The present study confirms their account except for newly-born S. acanthias, which may be similar to larger S. blainvillii.

Other structures undergoing considerable change with growth of the animal are the dermal denticles. In the adult these have already been shown to be specific in form by Bigelow & Schroeder (1957, fig. 3). The differences are shown here to be evident in all stages of growth as illustrated in the series of denticle forms in Text-fig. 3. The figures show that the closest similarity between the species is in the newly erupted denticles of embryos of S. blainvillii and S. megalops, but even here the denticles differ sufficiently in lateral view to be easily recognisable. Likewise the adult form denticles of S. acanthias and S. blainvillii are closely similar in outline but differ in the shape and length of the anterior prolongation of the median longitudinal ridge.

Two other differences between the species have become apparent during the course of the study. The first of these is the pupil size, which in S. acanthias is only about ¼ of the horizontal diameter of the eye, but in S. blainvillii and S. megalops is ⅓ or ½ (Text-fig. 1). The second is the heavy-bodiedness of S. megalops compared with S. acanthias or S. blainvillii. This is also shown in Text-fig. 1 where it is obvious not only in profile but in the contour of the head. However, all three species, and particularly S. blainvillii and S. megalops, become heavier-bodied with growth. As a consequence, dimensions such as height of body or width of head, which could show the differences, tend to overlap, and hence no difference may be apparent when specimens of different total lengths are compared.

Squalus acanthias Linnaeus, 1758. Text-fig. 1, A-C; Text-fig. 3, G-N; Text-fig. 5, A-F.

This species was reported from New Zealand by Hutton (1872, p. 76) as Acanthias vulgaris Risso, 1826, a name at that time current for the white-spotted dogfish of the North Atlantic and Mediterranean which we now know as Squalus acanthias. In a later account, Hutton (1904, p. 54) listed the species as S. acanthias, as did Waite (1907, p. 8). Regan (1908, p. 46), believing that the white-spotted dogfish of southern South America, southern Australia and New Zealand differed from S. acanthias, referred it to S. fernandinus Molina, 1782, a species first described from Juan Fernandez, off Chile. As I have shown above, the type description of S. fernandinus is inadequate, but since the diagnosis includes the words “corpore tereti ocellato”, Molina's species is at least a member of the S. acanthias group. Regan regarded S. fernandinus as having a shorter snout, “praeoral length equal to or less than the distance from eye to first gill-opening, the praeocular length equal to the distance from anterior edge of eye to spiracle (more in S. acanthias, except in young examples).” Comparison of Regan's findings with data assembled on white-spotted Squalus species under various names from New Zealand, north western Atlantic, Argentina and Patagonia in Table I does not confirm the distinction of a southern circumpolar species. The data do indicate a tendency for the features cited by Regan to be affected by growth change. Thus with increase

in total length the preoral length decreases relative to the distance from eye to 1st gill-opening; likewise the distance from anterior of eye to spiracle decreases relative to the preocular length. The only data which do not fit this picture are those from Vaillant (1888), and perhaps those from Norman (1937) on Argentinian specimens, but in both cases the dimensions are extracted from illustrations in these authors. On the basis of New Zealand (and Australian) material I can find no reason for retaining S. fernandinus as a distinct species, while the close correspondence of Devincenzi's (1939) data with mine suggests that the Patagonian species which he recognises as S. lebruni is similarly S. acanthias.

Following Regan's (1908) account, Waite (1909), Phillipps (1921, 1927, 1928) and Thomson (1921) reported the New Zealand white-spotted dogfish as S. fernandinus, while Rendahl (1926) listed it as S. acanthias

Phillipps (1931, p. 360) rejected the name S. fernandinus for the New Zealand white-spotted dogfish and described it as a new species, S. kirki. This was based on a comparison of New Zealand material with S. fernandinus as described by Lahille (1928, p. 326) from a specimen off Argentina. But Lahille's account is not of a specimen of the S. acanthias group, but of a specimen having the features of the S. blainvillii or S. megalops-cubensis groups—i.e., the 1st dorsal spine over the middle of the inner pectoral margin, the distance from exposed origin of the 1st dorsal spine to 5th gill-opening less than the distance from anterior of eye to 1st gill-opening, and a uniform colour, without spots. It therefore follows that Phillipps's species, S. kirki, was described without reference or comparison to the S. acanthias group in which it belongs.

Whitley (1934, 1940) follows Phillipps (1931) and recognises S. kirki in Australian as well as New Zealand waters. Fowler (1941) lists it as a nominal species, since he had not seen material. Norman (1937, p. 9) synonymises S. kirki with S. lebruni (Vaillant, 1888) which he believes to be the only spotted Squalus in the

southern hemisphere. His diagnosis for S. lebruni is exactly the same as that given earlier for S. fernandinus by Regan (1908), and hence for the same reasons prevent the recognition of S. lebruni as distinct from S. acanthias. The synonymy of S. lebruni given by Norman includes, with interrogation marks, Molina's original description of S. fernandinus whose status, apparently, Norman could not definitely decide on Vaillant's (1888, p. 13) account of S. lebruni, based on seven specimens from “Baie Orange: Punta-Arenas” adds little more except that the largest specimen, 700 mm long, had upper teeth more or less tricuspid in form. However from Vaillant's description and illustrations (1888, Pl. 1, fig. 2a) it is apparent that the teeth of his largest specimen were peculiar and not seen in the other material.

The only remaining accounts of the New Zealand species are those of Richardson and Garrick (1953, p. 36) who in a provisional key to the Squalidae follow Norman in recognising S. lebruni, and Phillipps (1946, p. 14) who retains S. kirki as distinct from S. acanthias on the basis of minor differences in the teeth. The differences cited by Phillipps were made on comparison of North Atlantic and North Pacific specimens of S. acanthias with New Zealand material, but I am not able to confirm them in a similar comparison. Undoubtedly differences in the teeth are present from specimen to specimen, but these seem to cover as wide a range in New Zealand specimens as occurs in the North Atlantic and Australian specimens that I have had available.

The above resumé shows that none of the features suggested in the literature for separating the New Zealand white-spotted Squalus from its counterparts elsewhere in the southern oceans, or from the North Atlantic S. acanthias can be sustained. Moreover, comparison of my material with the excellent description of S. acanthias in Bigelow and Schroeder (1948, p. 455) and with a north-western Atlantic specimen kindly supplied by Mr. W. C. Schroeder, of Woods Hole Oceanographic Institution, has not shown any feature in dimensions, morphology or details of teeth, denticles or colour pattern in which they differ. The New Zealand species is therefore to be recognised as S. acanthias.

Through the courtesy of Mr. G. P. Whitley, Australian Museum, and Mr. A. M. Olsen, C.S.I.R.O., Tasmania, I have been able to examine Australian specimens which are likewise referable to S. acanthias. The synonymy for the Australian spotted dogfish parallels that of the New Zealand one, but should include also S. whitleyi Phillipps, 1931, which though illustrated by McCoy (1883, Pl. 75) as lacking preoral clefts is obviously S. acanthias.

The existence of two subspecies of S. acanthias in the northern hemisphere has been suggested by Lindberg & Legeza (1958, p. 1685). They recognise S. acanthias acanthias and S. acanthias suckleyi, both of which occur in the North Atlantic and North Pacific but apparently do not overlap in their distribution. S. acanthias acanthias has been found in the North Sea, Mediterranean, Black Sea, Sea of Japan, southern part of the Sea of Okhotsk, and north-eastern Japan, while S. acanthias suckleyi is recorded from California, Murman and the White Sea. The basis on which Lindberg and Legeza recognise their subspecies is the length of the anterior pectoral margin compared with the distance from the 5th gill-slit to the centre of the nostril. S. acanthias acanthias is a short-finned form, the length of the pectoral margin ranging from 60.0% to 89.9% (average 76%) of the distance from 5th gill to nostril, while S. acanthias suckleyi is long-finned, the pectoral ranging from 101.0% to 110.5% (average 106%)

To see where the New Zealand form of S. acanthias fits into this picture, measurements of ten specimens 230 mm to 990 mm long were made. These had a range of pectoral length from 65.0% to 98.0% of the distance from 5th gill-opening to nostril. This range overlies the greater part of that for the short-finned S. acanthias acanthias, but also bridges the gap between the two subspecies. It was noted that the pectoral length increased relative to the 5th gill-opening to nostril length with

growth, hence to give a clearer picture the data from the New Zealand specimens and from Lindberg and Legeza were plotted against total length (Text-fig. 4). This shows a considerable reduction in the percentage ranges of Lindberg and Legeza's subspecies when only specimens of comparable size are examined—e.g., in the sizerange 630 mm to 900 mm total length, S. acanthias acanthias has percentages of 79. 0% to 90.0% S. acanthias suckleyi 101.0% to 110.5%, and the New Zealand specimens 82.0% to 91.0%. The New Zealand specimens clearly fit to S. acanthias acanthias. However it is unfortunate that Lindberg & Legeza have so few data for S. acanthias suckleyi, particularly from specimens of smaller size. Additional data might well show even less distinction between the subspecies, or possibly invalidate them.

The distribution of S. acanthias in New Zealand is essentially southern. The species is common on the continental shelf in Cook Strait and southwards on the.

Length of anterior margin of pectoral fin as % of distance between pectoral origin and centre of nostril.

east coast, but information is lacking as to its presence on the west coast of the South Island. North of Cook Strait it ranges at least to Poverty Bay on the east coast, and possibly extends to East Cape. It is uncommon on the west coast of the North Island, but is known as far north as New Plymouth.

Its distribution elsewhere is widespread, and it or very closely related forms of the S. acanthias group are circumpolar, occurring in temperate, subarctic and subantarctic waters of all oceans. For details of the distribution see Bigelow & Schroeder (1957, p. 30).