13 



Description of a New Genus (G0NI0BASI8) of the Family MELANID.E and 

 eighty-two new Species. 



BY ISAAC LEA. 



[Read May 27th, 1S62.] 



Family MELAN1D.E. 

 Genus GONIOBASIS.* 



Testa vel conica vel fusiformi. Apertura rhomboidea, inferne subangulata. 

 Columella superne interdum incrassata. Operculum corneum, ad spiram 

 pertinens.f 



In my paper on the genus Trypanosoma, proposed by me, I mentioned tbe 

 importance of eliminating as many species as possible from Melania, which is 

 so enormously extended as almost to prevent the possibility of finding suitable 

 names for its species. In the Proceedings of the Academy, December, 1861, I 

 stated that Professor Haldeman's genus Lilhasia formed a very excellent group, 

 (n working up a very large number of the family Melanidte, obtained from tbe 

 Southern and Western States. I have, notwithstanding the divisions which had 

 been made, found myself embarrassed with that form of aperture, which is 

 quite different from the auger-mouthed (Trypanosoma) species and the Litlmstu, 

 to which latter they are most nearly allied. I mean those which usually, 

 though not always, have a slight thickening of the upper part of the columella 

 and no callus below, and which are also without the notch of Lithasia, although 

 subangular at base. In this subangular character they differ from Melania pro- 

 per, which are round or loop-like at the base. For this group I propose the name 

 of Goniobasis,% which will give us for our American Melanidce the following 

 genera, all of them having spiral opercula : 



Melania, § Lam. Anculosa, Say. lo, Lea. Lithasia, Hald. Schizosloma, Lea. 

 Strephobasis, Lea. Trypanosloma, Lea. Goniobasis, Lea. Anmicola, Gould anc: 

 Hald. 



* r»wst, angle, and ffxris, base. 



t This genus may be divided into two groups, one embracing the conical, the other 

 ■.he fusiform species, and these into smooth, plicate, carinate, &c. 



t Adams's Elimia takes in part of this genus. 



i Cuvier describes Melania as having long teutacula, the eyes being on the exterior 

 side about the third of the length. The eyes of Melania Virginica, Say, are at the ba6e 

 of short tentacula. I very much doubt if we have a single species in the United States 

 which properly belongs to this genus, which Cuvier considered amarula as ihe type and 

 Lamarck asperata as tbe type. 



t 



