3^9 



Costa Rica Miocene — Olsson 



217 



cular in form; beaks situated well forward and but slightly 

 back of the extreme anterior end of the shell; the beak itself is 

 small and loosely coiled over the small sunken lunule; sculpture 

 consists of about 13, low, wide, smooth ribs which fit so closel}^ 

 together that there are no interspaces between them; the ribs are 

 rounded in section on the umbos, wide and low ventall}^; the ribs 

 are largest about the middle, small and fading awa}^ on the poster- 

 ior and anterior dorsal submargins; interior concealed in a hard 

 sandstone matrix. 



Length 22, height 21, semi-diameter 6 mm. 



The first specimens of this interesting species was collected 

 by Mr. R. Terry from some Gatun sandstones in Quitana Creek, 

 a small tributary streams of the Rio Betey. In that locality, it 

 is an abundant species and occurs in small zones. 



It is related to the recent Pacific, V. crassicostata Sowerby 

 but is a much smaller species. 



Gatun Stage: Quitana Creek. 



Hill No. J, Ba7iana River. 



Subgenus PLEUROaiERJS, Conrad 



Venericardia Conradiana Gabb, var. limonensis, n. var. Plate 26, figs. 19, 20 



Cardita Conradiana Gabb, 188 1, Journ. Acad. Nat. Sci. Phila., vol, 8, 

 2nd series, p. 377, pi. 47, fig, 79. 



Shell small, subcircular, moderately convex; umbos high 

 and prominent, with small, inconspicuous beaks at the anterior 

 1-3 of the shell; the sculpture consists of about 18 heavy, gran- 

 ulated ribs, separated by somewhat narrower interspaces; interi- 

 or of the shell deep, the hinge with 2 cardinal teeth and a small 

 posterior and anterior lateral. 



Length 7.00, height 7.00, diameter of the left valve 

 3,00 mm, 



Gabb specimen described from the Pliocene beds of the 

 Limon Peninsula, measures ram in length. His enlarged 



figure is very similiar to the present shell, in its subcircular foi m 



