161 
V BNERIC ARBI A globosa. 
TAB, CCLXXXI X.-upper and middle figures. 
Spec. Char. Globose; costae 16 to 20,, carinated ; 
carinse tuberculated, tubercles compressed. 
var. a. Rather depressed, costae 20, tubercles dis- 
tant. 
var . P, Rugged, beaks prominent, costae 16, 
tubercles subimbricated. 
Syn. Chama sulcata. Brander , f. 100. 
F £w individuals of this species attain to three quarters 
of an inch in diameter ; the tubercles in var a. look like 
little bits of the ridges pinched up, and give the whole 
shell a considerable degree of neatness by their regu- 
larity, while in p. they are clumsy, irregular, and often 
very close together, and the stride of growth are more 
conspicuous also, thus it has a rugged aspect ; the beaks 
in var a. are sometimes prominent, thus there is a tran- 
sition from one variety to the other. The lunette is 
condate, convex, sunk beneath the beaks but very con- 
spicuous in both varieties; the margin is deeply toothed. 
This Venericardia is nearly related to Ven. imbricata 
of La Marck, but is more gibbose, much smaller, and has 
fewer costae, it may possibly be Ven. cor avium Env. de 
Paris p. 223, but the hinge does not agree precisely 
with the description, however I have seen no specimens 
with that name, and no figure is quoted. 
Very abundant in Barton and Hordwell Cliffs, speci- 
mens may be so chosen from the two varieties as to look 
like distinct species. 
