66 CONTRIBUTIONS 
groove passing from the termination of the hgament to the 
posterior margin. 
C. comis. Plate 2. Fig. 41. 
Description. Shell inflated, elliptical, smooth; beaks 
large; lunule broad and cordate ; teeth elevated and dis- 
posed to be conical; excavation of the palleal impression 
rather deep and sub-biangular ; cavity of the shell deep ; 
margin entire. 
Diam. .9, Length 1.1, Breadth 1.5, of an inch. 
Observations. Differs from the C. globosa in being more 
transverse, less capacious, in having smaller beaks and 
smooth exterior. About the umbones it is somewhat 
gibbous. 
C. Hydii. Plate 2. Fig. 42. 
Description. Shell somewhat inflated, subovate, trans- 
versely and thickly folded; beaks rather elevated and mi- 
nutely folded; lunule cordate ; teeth rather elevated and 
compressed ; excavation of the palleal impression sub- 
biangular; cavity of the shell rather deep ; margin entire. 
Diam. .7, Length 1.2, Breadth 1.4, of an inch. 
Observations. This species is less inflated than the 
comis, and differs from it in having beautiful folds over the 
beaks and the whole disk. 
I have great gratification in placing the name of one of 
our most distinguished conchologists tothis shell. Among 
