387 



Costa Rica Miocene — Olsson 



215 



lyength 18, height 12.50, diameter of the right valve 

 5.50 mm. 



This small species represented by a single right valve in our 

 collection appears to be a true Cardita^ its hinge being essential- 

 \y that of the recent West Coast Cardita laticostata Sowerby. 

 With the exception of a few doubtful species in the Eocene of 

 United States, true Cardita has heretofore not been found as a 

 fossil in the Americas and its recent American species are con- 

 fined to the Pacific coast. 



Compared with the recent Ca7'dita laticostata Sowerby, w^hich 

 is abundant along the Pacific Coast of Panama, the fossil shell 

 differs in its smaller size, smaller umbos and in form. Its lunule 

 is like that of laticostata. 



Gatun Stage: Banana River. 



Section CARD 1 TAfVIERA, Conrad 



Cardita matima, n. sp. Plate 32, figure 8 



Shell robust, solid, strongly inequilateral with the beaks 

 situated at the anterior extremity of the shell; umbos 

 large and full with strongly curved beaks above the small, 

 sunken lunule; outline of the shell from within is subrectangu- 

 lar with straight ventral and posterior sides which meet at 

 nearly right angles; vSculpture of about 18 strong, heavy cord- 

 like ribs, separated by interspaces 1-3 of their width; the ribs 

 are strongly nodulated on the disk and umbonal portion of the 

 shell, but below they are simply irregularly wrinkled; a deep 

 furrow extends from the beaks to the posterior extremity, just 

 above the umbonal angle; the rib forming the summit of the 

 ridge between the umbonal furrow and the hinge-line is larger 

 than those on each side; shell cavity deep with a crudely den- 

 ticulated ventral and posterior margin/ hinge large (broken in 

 our specimen), with a well-developed anterior lateral tooth in its 

 left valve. 



Length 30, height 25, semi-diameter 12 mm. 



