26 LAND AND FRESH-WATER SHELLS OF N. A. [PART IV. 



removing the species to the genus Melanopsis, seized the occasion 

 to deprive Mr. Say of his species, a meanness that has unfor- 

 tunately found many advocates amongst naturalists ( ?) whose 

 sole ambition appears to be, to write "nobis" as frequently as 

 possible. But, like M. Deshayes, these gentlemen, although 

 sometimes successful for a period, will all eventually find 

 themselves quoted where they have placed the authors they 

 have endeavored to despoil, — among the synonymes. 



Subgenus LITHASIA, Haldeman. 



Lithasia, Haldeman, Supplement to Mouog. Limniades, No. 1, Oct. 



1840. BiNNEY, Check List of Fluviatile Univalve Shells, June, 



1860. Lea, Proc. Acad. Nat. Sci., p. 54, Feb. 1861. Jour. Acad. 



Nat. Sci., V, pp. 258 and 354, March, 1863. Observations, ix, pp. 80 



and 176, March, 1863. 

 Lithasia, Ilaldeman (part.), H. & A. Adams, Genera, i, p. 308, Feb., 1864. 

 Lithasia, Lea, 1845, Ciienu, Man. Conchyl., i, p. 2'J6, 1859. 

 Megara (part.), Adams, Genera, i, p. 306, Feb., 1854. 

 Anculotus (sp.). Say, Gra\, Genera, Zool. Proc, pt. 15, p. 153, 1847. 



Reeve, Monog., April, 1860. 

 Anculosa (sp.). Say, Auct. 

 Melania (sp.), Auct. 



Description. — Shell ovately fusiform or oval, small, smooth. 

 Aperture not so distinctly channelled in front as in the typical 

 Angitremce. Columella with an anterior and posterior callous 

 deposit. 



Geographical Distribution. — Like the t3^pical species, we find 

 the Lithasioi inhabiting principally the waters of Tennessee 

 and North Alabama ; but one of the species is completely 

 separated from the geographical area of the group, its habita- 

 tion being confined to the Ohio River and tributaries. This 

 shell, L. ohovata, is somewhat removed from the general type, 

 but is connected with it, by L. undosa, a Kentucky species. 

 Another allied shell, L. consanguinea, has heretofore been found 

 in Indiana only. 



