152 NEW UNIONID^, MELANID^, ETC., 



spire somewhat elevated ; sutures impi'essed ; whorls nine, flattened ; aperture 



rather small, somewhat constricted, elliptical ; outer lip acute, subsinuous ; columella 



thin and somewhat twisted. 



Operculum ovate, very thin, light brown, with polar point near the base on the 



left side. 



Proc. Acad. Nat. Sci. 1864, p. 113. 



Hah. — Big Prairie Creek, Alabama, Dr. Showalter. 



My cabinet and cabinet of Dr. Showalter. 

 Diam. -25, Length -74 inch. 



Remarhs. — A single specimen of this species was received. It was sent with speci- 

 mens of what I called T. mucronatum, but while it has nearly the same color of 

 epidermis and is nearly of the same outline, it is distinguished by its longer base, its 

 having no carinations except on two or three of its fii'st whorls. It also differs in 

 the base of the columella, which is not so much curved. The aperture is also longer 

 and more constricted. The aperture is rather more than one-third the length of 

 shell. 



Genus MESESCHIZA.* 



Testa fusiformis, imperforata ; apertura rhomboidea, inferne canaliculata ; labrum expansum, in medio ex- 



cisum ; columella laevis, incurvata. 

 Operculum corneum, ad spiram pertinens. 



Proc. Acad. Nat. Sci., 1864, p. 2. 

 When I described the genus Trypanosiomaf I mentioned the importance of elimi- 

 nating as many species as possible from the enormously extended genus Melania. 

 The little shell which I now propose as a new genus has so distinct a character in 

 the incision of the middle of the outer lip, as to mark distinctly its place in the Mela- 

 nidce of the United States. It differs entirely in the character of the cut from that in 

 Schizostoma, which has, in all the many species I have seen, a more or less deep in- 

 cision immediately under the suture. The living soft parts have not yet been 

 observed. They may when examined prove to have some characteristics quite 

 different from Schizostoma. 



Meseschiza Grosvenorii. pi. 23, fig. 67. 



Testa Isevi, fusiformi, tenui, obtuse conica, vel purpurea vel vittata ; spira obtuse coDica ; suturis leviter 

 impressis ; anfractibus instar septenis, vix convexis; apertura magna, rhomboidea, intus plerumque 

 vittata ; labro acuto, in medio leviter exciso ; columella leviter incrassata et contorta. 



* Me™ a-x,i^n central fissure. 



t Jour. Acad. Nat. Sci,, Vol. v. p. 268, and Obs., Vol. ix. p. 90. 



