APPENDIX. 
27 
Subgenus Callicakdia, Conrad'. 
Of this elegant species, Dr. Gray remarks, that 2 odd valves have been 
dredged up from deep water, one valve in the Sooloo seas and the other 
in the Yellow Sea. It the fossil species had the same kind of station we 
might infei that they indicated deep water in the ocean where they lived. 
P achycabdkiji, Conrad. is very different from this genus, being more 
elevated, with prominent summits, direct, and having no angle to the 
mnbonal slope limiting the radiating lines to the post-umbonal slope, but 
the radiating lines are on part ot the disk. Unlike Pkotocakdia there is 
no form nearly related to it in a Tertiary formation. 
CYPRIMERIA. 
The many perfect valves found at Snow Hill enable me to give the fol- 
lowing diagnosis of this genus : 
Shell inequivalved, bent to the right, dorsal area excavated, hinge of 
right valve with 3 cardinal teeth, and a wide triangular pit under the 
apex, which is ridged or uneven ; left valve with 3 cardinal teeth, the 
posterior one very oblique, narrow, lobed or bifid, the lobes linear ; pallial 
line with a slight sinus. 
The above generic character excludes from this genus obesa d’Orbigny, 
Oldhamiana , Stoliczka, and analog a, Forbes, which are referred to it by 
Stoliczka, and indeed I do not find recorded in his Palaeontology of South- 
>ern India a single species of Cypkimeeia. His species, whatever [the 
hinge may be, are all without fold and equivalve. Arcopagia numismalis 
and A. rotundata , d’Orbigny, are typical species. Lucina discus , Math- 
eron, is a fine species, well figured by Dr. Zittell, under the name of 
Circe discios. C. dcnsota, Conrad, a large species from New Jersey, fig- 
ured in vol. 3 of Journal of Acad. Nat. Sciences, Second Series, is very 
different from the species of the same name in vol. 2, which may be 
named C. alia. 
YENILIA. Morton. 
Stoliczka repudiates this name and substitutes one of his own. There 
is no recognized name of Venilia in Conchologv, except that given by 
Morton. Stoliczka has described some shells which he plaees in this 
genus which, however, belong to another, and all the species which he 
refers to Cypkin a are true species of Venilia. 
