66 CONTRIBUTIONS 



groove passing from the termination of the ligament 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. 



Diara. .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. Hydti. 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. 



Diara. .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 to this shell. Among 



