TRANSACTIONS OF WAGNER 

 1508 



TERTIARY FAUNA OF FLORIDA 



their external resemblance to Cuspidaria were placed with the latter genus and 

 not discovered to be different until it was taken up for study. The group 

 seems likely to belong in the Corlndidce, but owing to the circumstances above 

 noted it finds a place here. 



Spheniopsis americana n. sp. 



PLATE 57, FIGURES 28, 29. 



Oligocene of the Chipola River, Calhoun County, Florida; Burns. 



Shell small, equivalve, rostrate ; beaks small, pointed, subcentral ; sculp- 

 ture of a few, nearly concentric, relatively large waves, sometimes obsolete, 

 and fine concentric striation; dorsal slopes steep, forming an angle of nearly 

 ninety degrees at the umbones ; the anterior end rounded, base arcuate, pos- 

 terior end rostrate, slightly twisted, subtruncate terminally; hihge in the right 

 valve of two diverging relatively strong lamellar teeth, between which is the 

 resiliary pit and above which the margins are grooved to receive those of the 

 opposite valve, which is edentulous ; the fossette is subumbonal and not ele- 

 vated ; the muscular impressions are distinct, as is the pallial line, which has 

 a short, wide, rounded sinus ; the inner margins are entire. Length 3, height 

 2, diameter i mm. 



The waves near the beaks are inconstant in strength and extent, but seldom 

 cover more than a third of the disk. 



FAMILY POROMYACID^E. 



Genus POROMYA Forbes. 

 Poronmya Forbes, Rep. Moll. fiLg. Sea, p. 143, 1844. 

 Embla Loven, Ind. Moll. Scand., p. 46, 1846; Gray, P. Z. S., 1847, P- *93- 

 <Poromya Ball, Bull. Mus. Comp. Zool., xii., p. 280, 1886; Bull. U. S. Nat. Mus. No. 



37, P- 68, 1889. 

 Type Poromya anatinoides Forbes, = P. granulata (Nyst) = Corbula granulata Nyst, 



1839- 



A single species of this group has been described from our Tertiary. 



Poromya mississippiensis Meyer and Aldrich. 

 Poromya mississippiensis Meyer and Aldrich, Bericht Senckenb. Nat. Ges., 1887, p. 10, 



pi. ii., figs. I, la, ib. 



Jacksonian Eocene of Jackson, Mississippi, and Garland Creek, Choctaw 

 County, Alabama; Burns. 



This is marvellously like the recent and typical species, but differs in having 

 the small granules arranged quincunxially instead of in distinct radial series. 



