367 Costa Rica Miocene — Olsson 195 



Gatun Stage: Hill i, la, Bana^ia River, typical and var. 



suberversa 

 Coll. 7, Puinbric Creek {^typical') 

 Coll. 6, Red Cliffy Creek {typical) 

 Be ley {subreversa) 

 Zone G, Saiiry {subreversa) 



Genus PTERIA, Scopoli 

 Pteria inornata Gabb Plate 28, figure 9 



Avicula inotnata Gabb, 1873, Trans. Amer. Phil. Soc, vol., 15, p. 



253- 

 Pteria inornata Dall, 1898, Trans. Wagner Free Inst. Sci., vol, 3, pt. 



4, p. 669. 

 Pteria inornata Maury, 1817, Bull. Amer. Pal., vol. 5, p. 345, pi. 26, 



fig. 14. 



This species is locally common in Costa Rica, but generall}^ 

 difficult to collect because of its thin and fragile shell. Its 

 valves are as high as long, strongly convex and smooth. The 

 anterior ear is of medium size, the posterior much larger and 

 produced. 



It was described as a Miocene fossil from Santo Domingo, 

 but has also been collected at Bowden. 



Uscari for-rnation. Old Harbor. 

 Gatun Stage: Zone j; Red Cliff Creek. 



Genus OSTREA, Linnaeus 



Ostrea megodon Hanley Plate 18, figure I 



Ostrea megodon Hanley, 1845, Proc. Zool. Soc. London, p. 106. 

 cf. Ostrea cerrosensis Gabb, 1869, Geol. Surv. Calif., vol. 2, p. 35, pi. 

 II, fig. 6i. 



Ostrea megodon Dall, 1897, Trans. Wagner Free Inst., vol. 3, pt. 4, p. 



685. 

 Ostrea megodon Maury, 1917, Bull. Amer. Pal., vol. 5, p. 347, pi. 34, 



fig- 3- 



