FRESHWATER AND LAND SHELLS. 93 



ing a sharp carina, which is placed on the inferior part of the superior 

 whorls. In its numerous striae it resembles the M. muUilineata (Say), 

 which is now I believe acceded to be only a variety, much striated, of M. 

 virginica of the same author. Most of the specimens which have come 

 under my notice are white inside, with a purple spot on the columella, 

 and an indistinct light band along the inferior part of the suture. Some 

 individuals are, however, entirely purple inside, and this gives the epi- 

 dermis quite a black appearance. 



Note. — When I described a Melania under the name of tuberculata,! had not seen Spix's 

 work on the fresh water shells of Brazil. Finding there the same name used for a Melania, 

 mine must of course be changed, and I would propose the name of Spixiana for it. 



Melania plicifera. Plate XXIII. fig. 90. 



Testa acuto-turrita, subcrassa, tenebrosa ; spira plicifera ; apice truncato ; anfractibus 

 convexiusculis, ultimo supernt Icevi, infernh striato ; apertura alba. 



Shell acutely turrited, rather thick, nearly black; spire full of folds; apex truncate; 

 whorls somewhat convex, the last being smooth above and striate below ; aperture 

 white. 



Hab. Wahlamat, near its junction with the Columbia River. Pro- 

 fessor Nuttall. 



My Cabinet. 

 Cabinet of Professor Nuttall. 

 Diam. '4, Length 1*1 inches. 



Remarks. — Among the fine shells brought by Professor Nuttall from 

 beyond the Rocky Mountains, was this single species of Melania. It 

 is remarkable for its numerous folds, or ribs, which fill the superior 

 whorls. The inferior whorl is entirely without these ribs, but the 

 inferior portion is furnished with transverse striae. I am indebted to 

 Professor Nuttall for many specimens of this shell, all of which are 

 more or less truncate at the apex. The most perfect one, which is 

 small, has nine whorls. 



VI Y 



