426 MOLLUSCA. 
and hinge, it is almost identical. It is larger than any other species I 
have seen. 
Length seven-eighths of an inch; height six-eighths of an inch; 
breadth half an inch. 
Inhabits Hunter’s River, New South Wales. 
Figures 526, 526 a, lateral and dorsal views of the shell; 526 d, the 
hinge. 
CycLas PATELLA (Gould). 
T. parva, tenuis, rotundato-ovalis, lenticularis, modicé cavata, concentricé 
extliter sulcata, epidermide luteo-viridi induta; apicibus medianis, 
rotundatis, haud elevatis : intus lactea: cardo dentibus duobus minutis 
cardinalbus instructus ; dentibus lateralibus remotis, validis. 
Cyclas patella, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 292. 
Nov. 1850. Expedition Shells, 86. 
SHELL small, thin, lenticular, nearly equilateral, transversely 
rounded-oval, rendered somewhat triangular by the dorsal slope; 
somewhat pointed at beaks; surface finely grooved concentrically, 
and somewhat radiately striate at beaks. Valves regularly convex. 
scarcely modified by the beaks; epidermis pale greenish-yellow. In- 
terior creamy white, smooth; cavity of the beaks very shallow: hinge 
with two minute, diverging, cardinal teeth, and a distant, well-deve- 
loped lateral one on each side. 
Length half an inch; height three-eighths of an inch; breadth one- 
fourth of an inch. 
Inhabits Oregon, at Wallawalla and Vancouver. 
This is to be compared with C. cornea, on account of the peculiar 
rounded form of the dorsal region, the umbones not rising so as to in- 
terfere with the general outline. The cavity of the beaks is still more 
shallow, the sulcation coarser, and the colour yellowish rather than 

