. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Fauna at Canandai(;ua Lakk, N. \'. 85 The index of the nepionic shell is about to ; of the neanic .79 to .95, and of the adult .76 to .90. 'I'he average for ten specimens in neanic stages , and of a similar number of adults, .83. The shell substance is impunctate. Muscle Scars.—The muscular area is roughly shield-shaped with the broad end directed backward. The front end is about the middle of the valve. The area is very small, as compared with the size of the va
. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Fauna at Canandai(;ua Lakk, N. \'. 85 The index of the nepionic shell is about to ; of the neanic .79 to .95, and of the adult .76 to .90. 'I'he average for ten specimens in neanic stages , and of a similar number of adults, .83. The shell substance is impunctate. Muscle Scars.—The muscular area is roughly shield-shaped with the broad end directed backward. The front end is about the middle of the valve. The area is very small, as compared with the size of the valves. In a s|)ecimen mm. long and mm. wide the muscular area is mm. long and .86 mm. wide. In a smaller specimen, x mm , the area is .5 x .5 mm. In both valves there are narrow transverse scars on the anterior and posterior borders of the area. In the ventral valve, behind the an- terior transverse scar, are two large oval adductors. Their anterior ends nearly meet, and the posterior ends are widely separated. Back of them, at the corners of the shield, are two small round scars, and there is a double scar on the median line. In the dorsal valve the anterior adductor scars are narrow and par- allel. Behind them are two smaller scars and between them a median scar. Pholidops oblata Hall. (Plate II.) Hall, Pal. N. V., IV., 1S67, p. 414, pi. 3, fig. 10. Of this species there are about 200 specimens in the collection. The smallest is mm. long and i mm. wide. The largest is mm. long and 7 mm. v/ide. A specimen of this species described by Hall is about twice the size of the largest shell in our collection. It is mm. long and 14 mm. wide. Nepionic SJiell.—As in P. liainilionicc ,^ r,, ,? j , ,, j ^ riG. I. Pholidops oblata the nepionic shell is oval, broader than Hall. Nepionic and early ne- long, convex, and with a slightly curved anic stages, drawn from a dorsal hinge line. The dimensions of the smallest l^eak. They might be termed shell of
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