*** The title of this work has been altered because the principal 

 term is pre-occupied among the zoophytes; and on account of the 

 great difficulty of getting the Mexican species. 



;H&enfte in his Synopsis methodica Molluscorum, has a con- 

 siderable number of "new" American species; but as the greater 

 part of them cannot be determined, and are from localities pre- 

 viously well known, and containing species described by American 

 authors, (one species may be found in Lister and Gmelin, and 

 several of them were described here in 1817,) I have not thought it 

 necessary to cite the work. Physa striata et subarata, are probably 

 P. heterostropha: Paludina sulculosa = subcarinata, Say: Melania 

 cruentata = Anculosa praerosa, Say: Melania curta et fasciata = 

 M. virginica, auct.: Melania livescens is probably the only species 

 to which he is entitled; and it was first noticed by Say, and from 

 the imperfection of his specimens, referred to M. virginica. It has 

 been recently named M. Niagarensis by Mr. Lea, 



Several well known species of our univalve shells have lately 

 been characterized as new, and as it is important that those of our 

 distinguished countryman Say, should be preserved in his name, I 

 do not hesitate to publish the following determinations on the pre- 

 sent occasion. 



Melania Warderiana, Lea, = M. simplex, Say. 

 " acuto-carinata, Lea, = " " 

 " Hildrethiana, Lea, = " obovata, Say. 

 " globula, Lea, = " subglobosa, Say. 



" virgata, Lea, = " " 



" Cincinnatiensis, Lea, = Anc. praerosa, Say. 



Anculosa dentata, Lea, = A. dentata, Couthouy. 



Melania catenaria, Lea. Name preoc. by Say. 



Lyranea fusiformis, Lea. Name preoccupied. 



lo tenebrosa, Lea, = Fusus fluviatilis, Say. 



Melania Kirtlandiana, Lea, = M. exilis, mei. 



Paludina angulata, x Lea; P. Coosaensis, Lea; P. bimonilifera, 

 Lea; and P. magnifica, Conrad; constitute but one species. 



