OF CONCHOLOGY. 109 



Dr. Brot, in his admirable "Systematic Catalogue of the Mc- 

 lanians," proposes, instead of the genera of H. & A. Adams, a 

 series of sections, which are generally excellent, for the ar- 

 rangement of the species. The following is his plan : — 



1. Opercxilinn concentric. 



Genus Paludomus, Swainson. 



2. Operculum sjiiral or snhspiral. 

 * Aperture entire. 



Genus Leptoxis, Eaf. 

 [Anculotus, Say; Ancidosa, Conr.) 

 Genus Melania, Lam. 

 Group a, tj'pe canalicuIxUa, Say. 

 " b, " curvilahris, Anth. 

 " c, " Haysiana, Lea. 



f a, type Virglnica, Say. 

 [ 5, " costulata, Lea. 

 " 0?, \ c, " perangulata, Conr. 



d, " simplex, Say. 



e, " Warderiana, Lea. 

 " e, " nuj)era, Say. 



" f, (European.) 



i a, " lavissima, Sowb. 

 " (J, "I b, " glajjhyra, Morelet. 

 ( c, " w'gritinn, Morelet. 

 (All the other groups of this section, thirteen in number, are 

 exotic.) 



** Aperture produced in front. 



Genus lo, Lea. 

 ^''^•'^' Apierture truncate in front. 



(Melanopsis, Hemisinus.) 

 *^*^' Aperture p>osteriorly sinuate. 



Genus Gyeotoma, Shuttlw. 

 *'^"'^** Aperture sinuate in front and posteriorly . 

 (PiREXA, Lam.) 



Passing to American authors, we find Mr. Say was the first 

 to eliminate a native genus from the genus Melania. In his 

 description of Melania prairosa, he says, "This shell does not 

 seem to correspond with the genus to which I have for the pre- 

 sent referred it ; and, owing to the configuration of the base of 

 the columella, if it is not a Melanopsis, it is probable its station 

 will be between the genera Melania and Agathina. I propose 

 for it the soneric name of Anculosa.^^ 



