36i 



Costa Rica Miocknk — Olsson 



Gahm Stage: Hill z, Bajiana Rivej . 



Coll. 5, Red Cliff Creek. 

 Rio Blafico. 



Old Man Sam Creek, i 7nile south of beach. 

 Area Veatchi, n. sp. Plate 23, figures 1-3 



Shell large, moderately convex; in outline, the shell is near- 

 ly square with the height about equal to its length; the anterior 

 side is widely rounded to the ventral margin, the posterior side 

 nearl}'- straight, nearly at right angles to the hinge-line; umbos 

 wide, with the unbonal angle widely rounded and with the ex- 

 treme tip of the beaks situated at the anterior 1-3 of the total 

 length of the shell; right valve with about 45 ribs, of which the 

 posterior 14 are on the posterior-dorsal slope; the ribs are rec- 

 tangular in section with the interspaces on the center of the 

 disk about 3-4 of the width of the ribs; the ribs are finel}^ scul- 

 ptured but less strongly on the right valve; on the center of the 

 shell disk, the ribs are finely nodulated or granulated but on the 

 posterior-dorsal slope and on the anterior extremity, the granu- 

 lations of the ribs is gradually overshadowed by the introduc- 

 tion of 4 or 5 fine, threads on the top of each rib the interspaces 

 on the center of the disk of the left valve are finel}'^ sculptured 

 with even, raised concentric threads; the left valve is slighth* 

 larger and overlaps to a small extent the right; hinge-line 

 straight with numerous small teeth, larger and higher at the ex- 

 tremities; cardinal area that of typical Scapharea, and grooved 

 with 3 lines; interior of the shell deep, with the posterior ad- 

 ductor scar about twice the size of the anterior; basal margin 

 fluted in harmony with the external sculpture. 



Length 51, height 51, diameter 41.5 mm. 



This is a rather large, Cardium-lik.^ Area of nearly square 

 outlines and numerous finely sculptured ribs. Its form is also 

 suggestive of Argina, but its cardinal area is that of a true 

 Scapharca. The type specimen, a finely preserved individual 



