JSfelson on Tertiary 3follusca of Peru. 203 



Chione, sp. ind., b. 



A species closely related to Chione aniathiisia Phil., is represented 

 by three specimens in very poor condition. In form it agrees very 

 closely with the typical forms of Chione amathusia, but it appears to 

 have been a thicker shell ; the lunnle is proportionally broader, the 

 breadth nearly equaling the length. The " concentric frills " are much 

 more numerous, but as the hinge line can not be seen the exact rela- 

 tions of this species can not be made out. 



Length 46 millim.; breadth 54*4 millim.; height 34-6 millim. 



Crassatella gibbosa Sby. 



C. gibbosa Sowerby, Proc. Zool. Soc, London., p. 56, ]832. 

 Plate VII, figure 9. 



Shell oval, very gibbous, marked by strong, flat, concentric lines ; 

 surface smooth. Umbos depressed, undulate. Anterior margin 

 regularly rounded, short, with the lunule very deeply impressed. 

 Posterior margin longer, distinctly angulate, and strongly ridged; 

 ligament area very long and narrow. Hinge line nearly straight; 

 teeth divergent ; cardinals bifid ; surface betAveen cardinals coarsely 

 crenulate ; remaining surface of hinge area finely nodulose ; fossette 

 large and triangular. Young shell depressed and surface undulate. 

 Three specimens give the following measurements ; 



Length, 10-4 millim. Breadth, 15'2 millim. Heipht, undetermined. 



" 20-0 " '■ 26-4 '• '• " 



" 63-1 •' '• 76-4 " '• 39-4 millim. 



This species is of special interest. I have been unable to find any 

 constant characters of difference between our specimens and those of 

 C. gibbosa Sby., in the Museum of Yale College. Differences observed, 

 also, are mostly due to age. The shells are more gibbous ; lunule more 

 deeply impressed; and ligament scar straighter and proportionally 

 longer than in any living specimens which I have examined. But as 

 they agree so closely in all other respects, even to the crenulations of 

 the teeth and the nodulous character of the depression of the right- 

 valve, into which the corresponding lateral tooth fits, and the annular 

 markings of the muscular scars, our species can not be regarded as 

 anything more than a variety of C. gibbosa. Our specimens are larger 

 than the type of Sowerby, or any of the specimens of that species in 

 the Museum of Yale College. 



Cardium, sp. md. 



Shell oval, large, very convex ; ribs strong and rounded, well ele- 

 vated, as broad as the spaces between them, about six in the space of 



