with a revision of the Limnandce of Authors. 353 



Genus Pom/pholyx. Lea. 1856. 



Tentacles medium, stout, cylindrical, slightly globose at the 

 tips. Genitalia on the left side. Teeth (See figure I.). 



Shell few-whorled, last whorl ventricose. Aperture oblique, 

 obtusely angulate below, entire. 



Type Pompholyx cjfusa. Lea. 



Genus Choanomphalus. Geretfeldt.* 1860. 



Animal unknown. 



Shell deeply umbilicate, resembling Tropidina. 



Type Choanomphalus Maachii. Gerst. 



Genus Carinifex. W. G. Binney.f .1863. 



Soft parts resembling Planorbis. Tentacles apparently 

 shorter. (Lea.) 



Teeth (See figure II.). 



Shell with angulated whorls and a wide funnel-shaped um- 

 bilicus. 



Type Carinifex Newberryi — Planorbis Newberryi. Lea. 



Sub-genus Vorticifex. Meek. 



Whorls rounded above. Adult shell smooth or marked by 

 lines of growth. Young shell provided with strong transverse 



costse. 



Type Vorticifex Tryoni, = Carinifex Tryoni. Meek. 



Fossil in the Tertiaries of Nevada. 



The above name is proposed by Mr. Meek for the remark- 

 able form above indicated, which was obtained by the U. S. 

 Geol. Survey, of the 40th parallel, under Clarence King. 



* Mem. St. Petersburg Acad. Sci., ix. p. 527, 1800. See also Revue et Magas. 

 de Zool. 18G0, p. 527. PI. 23. The typical species beam no little ifWIttiltnon 

 to Carinifex, and, though Hmaller, may be congeneric. It has several years' 



priority. 



f Merjanyntropha. Lea. Neither genus was characterized by the author, and 



the former is in general use and has priority. 



