PELECYPODA—TELEODESMACEA. 



549 



CXLVIII. Caprina d'Orbigny. 



Very inequivalve, attached by the coniform right valve which is 

 marked only with growth lines and possesses an almost internal 

 ligament groove. Hinge margin, with several deep cartilage pits 

 and with one large posterior tooth. Left valve large, spirally 

 twisted ; anterior tooth supported by a plate which divides the 

 umbonal cavity lengthwise ; posterior teeth obscure. Inner layer 

 of lower (right) valve made up of concentric lamellae between 

 which cavities are sometimes left. The middle layer of the free 

 valve traversed by numerous simple, wide, parallel canals, extend- 

 ing from the margin to the apex. A series of depressions present 

 between the posterior adductor scar and the margin. Comanchic. 

 520. C. crassifibra Roemer. (Fig. 752.) Comanchic. 



Larger free valve spiral, tortuous or sickle-shaped. 



Upper Fredericksburg and lower Washita : Texas. 



Fig. 752. Caprina crassifibra ; a, complete valve, partly worn towards the end 

 6, section of the same. (After Roemer.) 



521. C. occidentalis Conrad. (Fig. 753.) Comanchic. 



Sickle-shaped, flattened on the side of the outer curve, convex 



on the opposite side. Outer margins acutely rounded. Surface 



