200 Nelson on Tertiary Molhisca of Peru. 



LAMELLIBRANCHIATA. 



Pholas, sp. ind. 



This genus is represented by one very badly broken specimen. 

 Generic characters quite distinct, but not sufficient for specific deter- 

 mination. Length (from umbo to middle of ventral margin) 30 "4 

 millim. ; breadth 32 millim. ; height 32 millim. 



Panopaea, sp. ind. 



A broken valve, apparently belonging to this genus, occurs in this 

 collection. No species of this genus has been described from the 

 Panamic fauna, and only one species from the west coast, the 

 P. generosa Gould, from Puget Sound. Our specimen, if perfect, 

 would have had a length of perhaj^s 15 centim, and a breadth of 

 7'50 centim. 



Corbula Bradleyi, sp. uov. 



Shell very ventricose ; wedge shape, umbos large, convex, incur- 

 ved over the hinge area. Anterior margin rounded ; lunule very 

 deeply impressed ; ligament area twice the length of the lunule ; 

 strongly angulated with the posterior margin. Hinge tooth large, 

 recurved; fossette triangular and deeply impressed. Surface of 

 shell marked by strong, convex, concentric lines, separated by nar- 

 row but well marked spaces, about five of the lines in five millim. 

 Length 18 "8 millim. ; breadth 20 millim. 



The triangular shape is very characteristic, as also the angulation 

 of the posterior margin ; beak very prominent. 



Corbula, sp. ind. 



A single valve of this species was found ; it differs from the pre- 

 ceding species in being much less elongated and having much finer 

 concentric striation. Shell oval ; beak small. Anterior margin 

 rounded; posterior acuminate and elongate; tooth large, straight; 

 fossette rather small. Length 10 millim. ; breadth 14-8 millim. 



Solecurtus, sp. ind. 



This genus is represented by two broken specimens of a species 

 allied to S. affinis C. B. Ad. It difiers from that species in having 

 the callosity of the ligament much more evenly extended, and not so 

 acute, and the shell is more evenly elevated behind than S. affinis. 

 Our specimens are casts, except the posterior extremities. Length 26 

 millim. : breadth 66* millim. 



