266 Bulletin 39 438 



end about Y^ 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. 



Length 22, height 16, semi-diameter 4 mm. 



A rather thin, Do?iax-lik.e 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 GASTROCHAENA, (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 Gastrochcena was collected in 

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

 posterior portion and probably represents a j'oung shell of G. ro- 

 tujida 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 



? Corbula vieta Guppy Plate 28, figures 15, 16 



Corbida vieta Guppy, Quart. Journ. Geol. Soc. London, 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. 



