HANNIBAL: CALIKORNIAN FKESHAVATEIl MOLLUSCA. 151 



LiEVAPEx (Feurissia) undulatos (^Meek). 

 Ancylm undtdatus, Meek, 1877. 



Shell large, arched, apex posterior, slightly inclined, sub-prominent ; 

 habitat apparently lacustrine. 



Eocene : Truckee Lake beds, Nevada. 



The internal casts, of wliich all the specimens seen consist, retain 

 no trace of the sculpture, hence it is difficult to make certain the 

 generic position of this species. Aside from tlie large size it groups 

 very well with Ferrissia, but it is quite unlike the other AncyliruB 

 m the position of the apex. 



Genus Xeoplanokbis, Pilsbry. 

 Xeoplcmorbis, Pilsbry, 1906 {N. tantillus, Pils.). 

 Type, Neoplanorbis tantillus, Pilsbry. 



Sub-genus Amphigyea (Pilsbry). 

 Amphigrjra, Pilsbry, 1906 {^A. Alahamenns^ Pils.). 



Type, Amphigyra Alabamensis, Pilsbry. 



Sub-genus Atnphigyra. Shell minute, crepiduliform, dextral, spire 

 lateral, oblique, and smooth, body-whorl spirally striate, aperture 

 large and oblique, a broad concave septum projecting across the 

 posterior portion and reaching up into the spire, indicating an 

 appearance very early in the development ; habitat fluviatile. 



Sub-genus Neoplanorbis, s.s. Shell very minute, planorbiform, 

 dextral, coarsely spirally striate, more or less carinate at periphery, 

 spire sub-planulate, aperture oblique, columellar margin straight ; 

 AmpJiigyra stage apparently passed early in development ; habitat 

 rapid streams. 



Neoplanorbis (Amphigyea) Dalli (White). 

 Latia Dalli, White, 1882. 



Shell large for genus, apex small, terminal, sub-spiral, and slightly 

 oblique, apertui'e very large ; habitat apparently lacustrine, at least 

 in part. 



Eocene : Payette Lake beds, Idaho. 



This species is known to the writer only from White's original 

 descriptions and figures. It is obviously not -a Latia nor a Gundlachia, 

 but appears to resemble Amphigyra, and is placed here tentatively. 



Genus Fisheeola, n.gen. 



Type, Fisherola lancides, n.sp. 



Shell of moderate size, averaging 6 mm. in diameter, rounded-ovate, 

 somewhat broader anteriorly, depressed-conic, finely concentrically 

 striate, apex small, indistinct; sub-terminal, but not inclined; habitat 

 sluggish streams. 



Fisherola agrees with Lanx, s.g. Wallcerola, in general outline, the 

 medial position of the apex, and the absence of radial striae, while the 

 nucleus (shaped like a Chinese labourer's hat) is very similar, in 

 contrast to Ancylus, Acroloxus, or any of the Occidental genera. 



