95 



From Proceedings of the Academy of Natural Sciences of Philadelphia, September, 1802. 



Notes on American Fresh Water SHELLS, with descriptions of two 

 new Species. 



BY GEO. W. TYRON, JR. 



VIVIPARID.E, H. & A. Adams. 

 Vivipara, Montfort, 1810. 

 The following sub-genera of Vivipara inhabit the United States : 

 Tulotoma, Haldeman. Shell heavy and nodulous, opercle corneous and con- 

 centric; animal with the habit of Anculosa. 



Example. V. magnifica, Conrad. 

 V, bimonilifera, Lea. 

 Melantho, Bowdich, 1822. Shell oval, solid, sub-umbilicate or entirely covered. 

 Whorls smooth, aperture oval. Color uniform. 



Examples. V. ponderosa, decisa, etc. 



Haldemania, Tryon, 1862. Shell subcarinate, operculum with a paucispiral 

 nucleus, the accretions becoming concentric with age. 



Example. V. subcarinata, Say. 



There are several species of typical Vivipara inhabiting our Western waters, 

 all of which are entirely distinct from European species. 



V. lin eata , Valenc. (sp.) 



Paludina lineata. Valenciennes. Rec. d'Obs. de Zool. par Humboldt et 

 Bonpland, ii. p. 255, 1833. — Kiister, Martini and Chemn. Conch. Cab. 

 Monog. of Paludina, p. 10, 19, t. 2, f. 6—9 ; t. 4, f. 4. 1852. 

 " vivipara, Say, in Nicholson's Encyc. 3d. (American) Edit. t. 2, f. 5, 1819. 

 Haldeman, Monog. p. 17, t. 6. 



This shell differs from the vivipara of Europe in possessing four spiral 

 red bands, whilst the latter has but three. An examination of hundreds of 

 specimens from various portions of the Western States, and from Europe has 

 convinced me that the difference is permanent. 



V. intertexta, Say. 



This shell has occasionally, distinct red revolving bands, four in number. 

 I have a number of specimens from Davenport, Iowa, (Prof. Sheldon) ; and Mr. 

 Binney has one from Rock River, Illinois ; they diner from the New Orleans 

 specimens in the umbilicus being more open. 

 V. subpurpurea, Say. 



V. Texa n a , Tryon. 



T. solida, conica, pallide virente; spira elongata, sutura, valde 

 impressa, apice obtusa ; anfractibus senis, paulo-convexis, 

 apertura suborbiculata, parva, 2 — 5 totius altitudinis aquante. 



Length lj inch, breadth | inch. First five whorls of the spire 

 equal in length to the aperture. 



Hab. — Texas. 



Coll. Acad. Nat. Sci. Coll. G. W. Tryon, Jr. 



Shell solid, narrowly conic, consisting of six whorls, which 

 are somewhat flattened around their upper portion ; sutures well 

 impressed. Aperture suborbicular, equalling 2-5ths of the length 



