FAUNA OF ORTHAULAX PUGNAX ZONE. 101 



This species is represented only by one poor specimen, of which, 

 however, the genus is sufficiently recognizable. It was thought best 

 to put its occurrence on record and not await better material, which 

 it is to be hoped may eventually not be lacking. 



Family ASSIMINIIDAE. 



Genus ASSIMINEA Leach. 



Assiminca (Leach Ms.) Fleming, Hist. British Auim., p. 275, 1828. Type, 



A. grayana Jeffreys. 

 ? Assemania Knight, Jonrn. Conch. (Leeds), vol. 9, p. 296, 1900. 



ASSIMINEA ALDRA, new species. 

 Plate .5, fig. 9. 



Shell minute, of about 5 moderately rounded whorls with a dis- 

 tinct suture; spire tapering evenly to a somewhat blunt apex; sur- 

 face smooth; last whorl more than half the length of the shell; 

 aperture rounded ovate, peristome moderately thickened not re- 

 flected, a well marked layer of callus on the body; umbilical region 

 imperforate. Height 2, maximum diameter 1 mm. 



Tampa silex beds, at Ballast Point, Tampa Bay, Florida. One 

 specimen, E. J. Post, U. S. Nat. Mus. Xo. 166106. 



This is perhaps the oldest member of the genus which is reported 

 from the Pliocene or Pleistocene onl}^, as far as I can ascertain. 



Family EISSOIDAE. 



Genus RISSOINA Orbigny. 

 Rissoina Obbigny, Voy. Amer. Mer., 1840, p. 395. Type, R. inca Orbigny. 



RISSOINA SUPRALAEVIGATA, new species. 

 Plate 13, fig. 1. 



Shell small, smooth, subacute, with about 7 flattish whorls sepa- 

 rated by a feebly defined suture; nuclear whorl defective, the re- 

 mainder gradually increasing; last whorl rounded on the base, with" 

 a thick pillar lip ; outer lip protractively arcute, markedh'^ receding 

 toward the suture, slightly thickened; body with no perceptible 

 callus in the specimen. Length 5.5 mm., maximum diameter 2 mm. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida. 



Type-specimen from the Post collection, U. S. Nat. Mus. No. 

 165125. 



