62 
in length. Sculpture: Right valve, about 22—24 high regular ribs, 
bifurcating towards front and hind margins and becoming tripartite 
towards under margin by the appearing of a marginal furrow along 
each side of the ribs; interstices as broad as the ribs and sculp- 
tured with fine, close, concentric lamellae with serrated upper edges, 
or dissolved into isolated spinulæ; these lamellae extend on the 
lateral sides, and, though more or less worn off, on to the upper 
side of the ribs. Anterior ear with 5 coarse radiating ribs and a 
smooth area beneath running from sinus to umbo; bounding groove 
of the ear serrated by a series of small tubercles. Left valve: Ribs 
of the same number as in the right valve; concentric lamellae 
produced on the ribs into small imbricating scales. Colour of both 
valves orange rosy. Dimensions: max. h. 32, br. 29 mm. Locality: 
Campbell Island: 45, 10 dead valves, the small ones having a fresh 
appearance showing that the species belongs to the actual fauna. 
Its nearest ally seems to be Chlamys patagonicus King, which 
occurs in West Patagonia from 50® S to Tierra del Fuego and on 
the Eastern coast of Patagonia to 51® 30’ S as well as in the 
Falkland Islands (Hagg 1910). The chief differences between 
both forms are to be found in the greater number of ribs in the 
latter species (about 35 on the disc and in the right anterior ear 
6), together with a paler reddish-gray colour. The partition of the 
ribs is similar, but Chl. patagonicus often shows a bifurcating of 
the median ribs towards the inferior margin, and has, besides, an in- 
termediate riblet in each interstitial furrow; a similar intermediate 
riblet is totally absent in Chl. camphellicus. — The fossil Pecten 
triphooki, Z i tt el, which has been found fossil in Campbell Is¬ 
land (Marsh all 1909, p. 701), seems to be closely related, too. 
Chlamys (Pecten) dichrous Sut er. 
South Island: 29, many sps., h. 36. — Stewart Island: 31, 1 
sp., h. 31. — 35, 1 small sp. — Auckland Island: 37a, 3 valves, 
h. 12. 
Chlamys (Pecten) impavvicostatus Bavay. 
North Island: 11b, 1 sp., h. 7.2. 
Chlamys (Pecten) radiatus Hutton. 
North Island: 10, 2 sps., h. 26. — 14, 1 small sp. — 16, 
