405 Costa Rica Miocene — Olsson 233 



ranca near Punta Arenas on the Pacific coast of Costa Rica, 

 from beds probably equivalent to the Lower Gatiin or to the 

 Uscari. 



The shell is very thin and fragile, and hence the specimens 

 are ver}^ frequently much crushed and distorted in shape. Typi- 

 cally the shell is broad and high, the beaks anterior in position 

 and the surface sculptured with narrow, wave-like undulations 

 which are best developed on the umbos. 



Length 70, height 60. diameter 34 mm (Sousi Creek). 

 Uscari Stage: Sapote, C. Z. ( Gabb) 

 Gatiai Stage: Gatun, C. Z. 



Nancy'' s Cay, Prov. of Bocas del Toro. 

 Upper Hone Creek, and its tributary Sousi 

 Creek. 



Genus GAFRAR8UIV1, Bolton 



Section GOULDIA, C. B. Adams 

 Gafrarium limonensis, n. sp. Plate 32, figure 18 



Shell small, subcircular, moderatel}^ convex, umbos inflated, 

 beaks anterior to the middle: surface finely sculptured with even, 

 concentric riblets, more or less cancellated by fine, radial threads 

 which are strongest on the anterior and posterior extremities, 

 while the concentric riblets predominate on the middle of the 

 shell; lunule distinct, narrowly lanceolate; interior of the shell 

 deep, the hinge of both valves with 3 cardinal teeth and an an- 

 terior lateral; ventral margin concentrically grooved but not 

 tangentially as in Transenella. 



Length 4.75, height 4.25, diameter of the left valve 

 1.50 mm. 



This small Gouldia, is fairly abundant in the Miocene coral 

 limestones of Port Limon, and is characterized by its small, con- 

 vex shell and subcircular form. Gabb has described a small 

 Gouldia from the Pliocene beds of the Limon Peninsula, but that 



