353 



Costa Rica Miocene — Olsson 



i8i 



Dr. A. C. Veatch from the Upper Gatun of Old Man Sam Creek 

 in eastern Costa Rica and a few specimens from the coral-reef 

 limestones of Port Limon. Although a very distinct species and 

 not to be confused with any other Pectunculid recent or fossil, 

 its characters have been generally misunderstood and its name 

 has often been applied to shells of the G. Imeatus group. 



The shell is of moderate size, strongly convex and inequila- 

 teral. The beaks are slightly posterior of the middle, with the 

 ligamental area entirely anterior to the beaks as seen in figure 7. 

 The surface is sculptured with numerous, moderatel)^ coarse, 

 radiating threads which are simple on the umbonal area but be- 

 come divided by 3 or more finer threads ventrally. 



Gatun Stage: Old Man Sam creek. 

 Port Limon. 



Glycymeris Lioydsmithi Pilsbry and Brown Plate 25, figures 8. 9, to 



Glycymeris Lioydsmithi Pilsbry and Brown, 1917, Proc. Acad. Nat. 

 Sci. Phila., vol. 59, p. 39, pi. 6, fig. 6. 



This is an abundant fossil in eastern Costa Rica, where it 

 frequently forms zones in the lower and middle Gatun. Its type 

 of sculpture of broad, smooth, rounded ribs, is strikingly like 

 that of G. subovata Say of the Miocene of eastern United States. 

 It differs in its higher and narrower umbos and by its nearlj^- 

 smooth cardinal area. 



The G. Lioydsmithi was described by Pilsbry and Brown, 

 from beds equivalent to the Gatun, near Cartagina, Colombia. 



Gatun Stage: Zo7ie j, East Grape Point Creek, C. R. 

 Coll. 5, Red Cliff Creek, C. R. 

 Headwater of Middle Creek, C. R. 



Genus ARCA Linnaeus 

 Area occidental is Philippi Plate 22, figure i 



Area occidentalis Philippi, 1847, Abbild. u. Beschr., 3, p. 14, pi. 17b, 

 fig. 4a-c. 



