lOS AMERICAN JOURNAL 



inflata, Lea. occidentalis, Lea.* 



Kirtlandiana^ Antli. Hogersii, Conr. 



mono dordo ides, Gld. suhcarinata, Ilald. 



" Subgenus Lithasia, Lea, (i. 308.) 



Shell thick, solid, ovate ; \vhorls gibbose or tuberculated at 

 the hind part; aperture subcanaliculuted and produced in 

 front ; inner lip with a callus posteriorly, subtruncate ante- 

 riorly. 



genicula, Hold. salehrosa, Conr. 



neritijormis, Desh.f semigrarMlosa, Desh." 



ohovata, Say. 



Chenu (Manuel de Conchyliologie) principally follows the 

 arrangement of Messrs. Adams. 



Lovell Keeve monographs separately Jo, Hemisinus, Ajicii- 

 lotns, and Melatomij and treats all the species not included in 

 those genera as Mdani<e. lie says, " Advantage might have 

 been taken of the labors of systematists to have distributed 

 them into further genera ; but more materials are needed for 

 their elucidation than we at present possess.":}: 



R. J. Shuttleworth (Mittheil. der Nat.-forsch. Gesellsch. in 

 Bern. No. 50, p. 88) proposed, July 22, 1845, a new Ameri- 

 can genus of fluviatile shells, which he charactei^ized as follows : 



" Gyrotoma. — Shell turreted ; columella incurved, above cal- 

 lously thickened ; aperture oval, subeffuse at the base ; lip sim- 

 ple, acute, narrowly profoundly fissured above. 



" Animal. — Operculum corneous, spiral." 



This forms one of the most distinct of the genera of Strepo- 

 matidse. Mr. Lea, however, anticipated Mr. Shuttleworth's dis- 

 covery. 



* = m some respects Mudalia, Hald., and Somalogyrus, Gill, 



t Neritiformis, Desh., is an Anculom, and is a syn. of A. prarosa, Say. 



X It is very much to be regretted that Mr. Reeve did not make some kind 

 of a division, however arbitrary, of the immense material entering into 

 his magnificent monograph of Melanin, as he has published it. Species 

 from all countries, without regard to external resemblances, are, in many 

 cases, grouped on its plates indiscriminately, rendering the identification 

 of shells by its aid exceedingly dithcult. Even several of the species are 

 duplicated in description and illustration in the monographs of Melania, lo, 

 and ^nculotus. 



While on the subject of Mr. Reeve's monograph, we cannot refrain from 

 condemning the substitution of new descriptions of the species for those 

 originally given. The descriptions of Mr. Reeve in numerous cases en- 

 tirely neglect the most important specific characters. The plates frequently 

 do not represent the species for which they are intended ; but in this Mr. 

 Reeve has been undoubtedly deceived by wrongly-named specimens. 



It is a strange fact that, notwithstanding the length of time which has 

 elapsed since very many of our Melanians and Unios have been described, 

 and the large number which have been sent to Europe in scientific ex- 

 changes, European conchologists are still to a great extent ignorant of the 

 most prominent and important specific characters. 



