266 



BuivLETiN 39 



438 



end about again as long as the posterior, rounded; beaks 

 high, triangular; posterior and anterior dorsal margins straight; 

 ventral margin evenly rounded; surface nearly smooth; but with 

 the dorsal submargins finely concentrically grooved; interior 

 concealed. 



lycngth 22, height 16, semi-diameter 4 mm, 

 A rather thin, Donax-Y\^^ shell from the Lower Gatun beds 



of the Banana River. Its surface is smooth and polished with. 



concentric grooves on its posterior and anterior dorsal area. 

 Gatun Stage: Hill No. j, Banana River. 



Genus GASTROCHAEr^A, (Spengler) Cuvier 

 Gastrochaena rotunda Dall 



Gastrochcena ovata Sowerby, variety rotunda Dall, 1898, Trans. Wag- 

 ner Free Inst. Sci., vol. 3, pt. 4, p. 825. 



Gastrochcena rotunda Dall, 1915, Bull, N. S. Nat. Mus., No. 90, p. 157, 

 pi. 19, fig. 2. 



A single, small specimen of a GastrochcBna was collected in 

 the Gatun of Red Cliff Creek. It is widely expanded about the 

 posterior portion and probably represents a young shell of G. ro- 

 tunda which Dall records from the Bowden beds of Jamaica. 

 This species is also found in the Tampa Silex beds and in the 

 Lower Miocene of Florida. 



Gatun Stage: Coll. ^, Red Cliff Creek. 



Genus CORBULA, Lamarck 

 Section ALOIDIS, Megerle 

 ? Corbuia vieta Guppy Plate 28, figures 15, 16 



Corbula vieta Guppy, Quart. Journ. Geol. Soc. lyondon, vol. 22, p. 

 580, pi. 26. fig. 8. 



Corbula disparilis Gabb, 1873, Trans. Amer, Phil. Soc, vol. 15, p. 

 247. 



Corbula {Aloidis) vieta Dall, 1898, Trans. Wagner Free Inst. Sci., 

 vol. 3, pt. 4, p. 859. 



