lection. I am indebted to Mons. G. Mermod. Conservateur de Malacologie, for the following notes. “La Collection Lamarck, dans notre Musée, possède en effét un exemplaire de Pecten medius Lk. accompagné d'une étiquette de la main de Lamarck. Cette coquille mesure 60½ mm. de large, 53½ mm. de hauteur et 13 mm. d'épaisseur. Lamarck ne mentionne pas les dimension de son exemplaire, mais il n'en possèdait qu'un seul (d'après indications manuscrites de Lamarck, dans notre ouvrage, ayant appartenu à Lamarck).” This specimen (Plate 17, figs. 1–4) is here nominated lectotype of Pecten medius Lamarck. It is a small shell with about 13 rounded ribs, on the right valve, those near the front and rear showing secondary grooving. The left valve is distinctive: its ribs are almost as broad as the interspaces and regularly subdivided by secondary threads.

In a large series of New Zealand shells, the number of ribs is generally greater than in the type of medius. The interspaces of the right valve and ribs of the left are never so broad in relation to (respectively) the ribs of the right valve and interspaces of the left. Flatly-rounded smooth left valve ribs, considerably narrower than the interspaces, are diagnostic of the New Zealand shell: subdivided left valve ribs are unknown.

Pecten medius Lk. is, therefore, not applicable to New Zealand scallops. P. medius is, however, closely similar to a young specimen of P. maximus L. from the English Channel in which the secondary ribbing corresponds very precisely, and I have no doubt that Lamarck's type is a specimen of the European maximus.

Three syntype specimens of Pecten novaezelandiae Reeve, gummed to a tablet, showed only the left valves. Comparison with Reeve's figure (Conch. Ic., Pl. 8, No. 36) showed that the figured specimen is the largest of the three, and to confirm it, a slip of paper labelled “No. 36” was found inside the closed shell. Under normal circumstances, one would select the figured specimen as lectotype of novaezelandiae, but it is, unfortunately, a typical example of the Tasmanian scallop which Tate later named P. meridionalis. The specimen was removed from the slab, compared with meridionalis from d'Entrecasteaux Channel and later photographed (Pl. 16, fig. 1). It has 18 ribs with wide interspaces; smooth and flat-topped at first, with strong intercostal concentric lamellae, becoming rounder and subdivided by 2–5 secondary grooves towards the margin, where concentric sculpture becomes obsolete. The left valve and colour are also the same as in authentic meridionalis. A second, smaller specimen on the slab is also meridionalis.

Fortunately, a third specimen on the type slab of novaezelandiae is a pale example of the New Zealand scallop, and is here designated the lectotype, since it is clear that Reeve's description (Conch. Ic., viii) does not apply to the specimen figured. Reeve's description is quoted in full because Conchologica Iconica is not readily available. The statements italicised are considered to apply to the lectotype rather than to the figured syntype.

“The New Zealand Pecten. Shell somewhat elongately orbicular, equilateral, inequivalve; valves very minutely concentrically striated; left valve flat; rather concave near the umbo, a little immersed in the right valve, neatly rayed with fourteen rather narrow convex ribs,

whitish, stained with fawn-red; right valve expandedly convex, rayed with fifteen rather broader ribs, white; ears unequal, bent a little forwards towards the left valve.

“Hab. New Zealand; Hart.

“A beautifully symmetrical neatly-ribbed species, of a delicate subtransparent white, stained on the left valve with rich fawn-red.”

The lectotype is figured as Plate 15, fig. 6. It may be objected that there is no guarantee that this specimen was one of the original syntypes; in that case the specimen is a neotype, conforming with Reeve's description and with his intention of naming the New Zealand Pecten. The specimen figured by Reeve does not conform with either Reeve's description or his intention.

Reeve's figured specimen of Pecten medius Lamarck (Conch. Ic., Pl. II, No. 44) is apparently one of two full-grown individuals mounted on a slab labelled West Indies (Mus. Cuming). It is impossible to be certain which shell is the original of the figure. In my judgment they are New Zealand specimens. I could find no systematic difference from authentic New Zealand examples and have never seen shells from other localities which compare so closely. I conclude that the locality “West Indies” is incorrect. Presumably the specimens were acquired by the British Museum in 1866, when the bulk of the Cuming Collection was purchased (E. A. Smith, Hist. Coll. Nat. Hist. Mus., 2, 9: Mollusea). Smith records that many labels were displaced when the Collection was mounted on tablets by Mrs. Gray, but, in the present instance, the error occurred before 1852 (see also below under P. modestus).

Shells labelled P. laticostatus Gray, 1835, include seven of the northern subspecies, P. n. novaezelandiae, but another collected by Dieffenbach (probably at Chatham Island) has the characters of the southern form, named below.

Although pale in colour, the lectotype of P. novaezelandiae has the shell form of northern New Zealand scallops, and this permits the naming of a regional subspecies in southern New Zealand and the Chatham Islands.

Localities for P. n. novaezelandiae: North Auckland; Hauraki Gulf (beach to 38 fathoms); Mercury Bay; Waihi Beach; Opotiki; three miles west of Waitarere Beach, 25 fathoms (specimen with intercostal lamellae); Wellington Harbour, N.W. Corner, 40–50 ft.; Picton; Grove Reach, Queen Charlotte Sound.

Pecten novaezelandiae rakiura subsp. nov.

Southern populations of P. novaezelandiae differ from the nominate form in having squarer ribs with deeper interspaces, and in the presence of strong concentric intercostal lamellae, which are usually confined to anterior and posterior interspaces and to the ventral margin of the disc. In addition, many southern shells have fine radial grooves subdividing the ribs, and the pigmentation of the right valve, strongest in Auckland specimens, is reduced or absent. Most North Island left valves are initially concave, but flatten marginally. Most southern left valves are gently concave to the margins. The ribs on the left valve of northern shells are lower and have flatter tops than those of southern shells. Most of the characters noted vary indepen-

dently, so that individual shells from the north have concave left valves, traces of concentric lamellae, reduced pigment, secondary radial grooves, or squarish ribs, and individual southern specimens lack one or more of these features. There is inadequate material from intermediate localities to show whether there is a cline from north to south.

At present, it appears that the northern limit of populations referable to P. n. rakiura is in South Westland on the west and in South Canterbury on the east.

Length 107 mm.; height 91.5 mm.; inflation 23 mm. (holotype).

Length 137 mm.; height 111 mm.; inflation 33 mm. (largest paratype).

Localities: Chatham Islands; 2–8 fathoms, Port Pegasus; Bravo Island (type), Stewart Island; Wet Jacket Arm, Dusky Sound; Otago's Retreat, Preservation Inlet; off Cook's Saddle, Molyneux Bay, 25–27 fathoms (Nora Niven Station 13, 1907, Canterbury Museum).

Fossil Occurrences: G.S. 4996, north side of Rotokakahi River, Whangape Survey District. G.S. 3748, stream cutting south of Whitianga-Coroglen Road, 1¼ miles from Whitianga Wharf, Otama Survey District.

Some beach-worn shells from the shores of Cook Strait (Ohau River to Waitotara and Tahuna Beach, Nelson) have the intercostal lamellae and square ribs of rakiura, and strong grooves subdividing the ribs. In these characters they differ from most living shells from Wellington, Waitarere and Picton, and may be derived from buried Pleistocene deposits.

Shells from these Pleistocene deposits in the North Island are closer to rakiura than to novaezelandiae. This does not necessarily mean a northward movement during the Pleistocene since the diagnostic characters of rakiura are shared by the Castlecliffian P. tainui Fin. which ranged through the North Island.

Pecten modestus Reeve. pl. 16, fig. 2; pl. 18, figs. 1, 2.

P. bifidus Menke, Moll. N. Holl., 1843, 35 (non Muenster, 1836).

P. modestus Rve., Conch. Icon., 8, pl. II, fig. 41, 1853.

P. preissiana Iredale, Proc. Royal Zool. Soc. N.S.W., 1947–48, 18, 1949.

Three specimens ranging up to 97 mm. long, on a tablet labelled “Moreton Bay, M.C., Conch. Ic., xi, fig. 41,” are syntypes of modestus. The intermediate specimen is close to the size of the figure, and has a similar, but not identical colour pattern. It also differs in the weakness of the intercostal secondary riblets on the left valve: these are drawn conspicuously on the figure. In designating this specimen lectotype (J. de Conch., 90 (4), 1951), I concluded that it was the figured specimen, attributing discrepancies to artist's licence; this is questionable, and the figured specimen is probably lost, but the designation may stand, as the specimen agrees well with Reeve's description and is one of his syntypes.

Reeve states that the ribs of modestus are “characterised by a single groove running down the middle,” which his figure shows.

The two larger syntypes are typical specimens of the distinctive West Australian shell, with bicostate ribs on the right valve, and, as noted elsewhere, in the largest specimen, hidden within the closed

valves, I found a label reading. “Swan River, Dr. Bacon.” They closely resemble other shells from Western Australia.

Gray gave, but never published, a manuscript name to material collected by John Gould, and Iredale has recently described the Western Australian shell as Notovola preissiana, noting that P. bifidus Menke, 1843 (not of Muenster, 1836) is a synonym. However, as Cox notes (Proc. Malac. Soc., 18, 203, 1929), Pecten modestus Reeve is not invalidated by Pecten modestus (Gmelin), since the latter is a Chlamys.

Pecten fumatus Reeve, 1852

Pecten albus Tate, 1887.

Pecten meridionalis Tate, 1887. pl. 16, fig. 1.

The types of fumatus are inflated shells with smoothly rounded ribs, with concentric lamellae, on the right valve, strictly confined to anterior and posterior margins.

Iredale (P. Linn. Soc. N.S.W., 44, 193, 1924) believed that “all the southern shells tend to show” (intercostal) “striation while the northern ones are smooth.” The northern form is fumatus Reeve, which is related to a far-flung group of forms consisting of sinensis Sow. (China), puncticulatus Dunker (Japan), erythraensis Sow. (Red Sea), and the fossil Mediterranean benedictus Lam. (and its allies), and the fossil New Zealand marwicki Fin. (cf. Fleming, J. de Conch.). Consistent application of the polytypic species concept would entail treating all these as regional (or temporal) subspecies.

In South-eastern Australia and South Australia, the scallops tend to have squarer ribs than the fumatus group, and intercostal lamellae, and Tate's name albus, based on a South Australian shell, has been used by Iredale and by Cotton and Godfrey (Moll. S. Aust., 1, 92, 1938). Material available to me is insufficient, and its localisation too unreliable, to state whether a further geographic form intervenes between fumatus and albus. Evidence as to the geographic range of the named forms is at present conflicting. Iredale (Linn. Soc. N.S.W., 44, 194) considered shells from deep water off Twofold Bay to be near the Tasmanian meridionalis. In the British Museum, there is material of fumatus, contrasting strongly with meridionalis, labelled as “Dredged in George Bay, Tasmania (J. H. Ponsonby, Esq., registered, 93.3.2.425).” Presumably this is off St. Helens, on the east coast of Tasmania, but if authentic, it means that there are two forms in Tasmania. To add to the difficulty of defining distribution areas, specimens labelled “Northern Territory, Australia,” in the Dominion Museum, Wellington (presented Mr. Cornwall, February, 1949), are close to meridionalis. Iredale (Gt. Barrier Reef Exped., Brit. Mus., Vol. 5 (6), 365, 1939) considered the northern limit of the genus to be Keppel Bay, Queensland.

P. meridionalis and P. fumatus are members of different groups of Pecten which have had a long history of separation, and a complex history of distribution changes during late geologic time (cf. Fleming, J. de Conch., 90 (4), 1951). Such a history would account for an irregular mosaic distribution pattern in Eastern Australia.

Chlamys gemmulata gemmulata (Reeve). Plate 19, figs, 4, 5.

Reeve's figured specimen (Conch. Icon., 8, fig. 111) is the smallest of three on a tablet labelled “Moreton Bay,” and “New Zealand.”