XVll 



in^ata Lea. occidentalism Lea.* 



Kirtlandiana, Anth. Rogersii, Conr. 



motiodontoides, Gld. subcarinata, Hald. 



" Subgenus Lithasia, Lea (i, 308). 



Shell thick, solid, ovate ; whorls gibbose or tuberculated at 

 the hind part ; aperture subcanaliculated and produced in front ; 

 inner lip with a callus posteriorly, subtruncate anteriorly. 



genicula, Hald. salebrosa, Conr. 



nei-itiformis, Desh.f semigranulosa, Desh." 



obovata, Say. 



Clienu (Manuel de Conchyliologie) principally fol- 

 lows the arrangement of Messrs. Adams. 



Lovell Reeve monographs separately lo, Hemis- 

 inus, Anculotus and 3IeIafoma, and treats all the 

 species not included in those genera as Melanice. 

 He 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. Ge- 

 sellsch. in Bern., No. 50, p. 88) proposed, July 22, 

 1845, a new American genus of tiuviatile shells, 

 which he characterized as follows : — 



*= in some respects 3IudaUa, Hald., and Soniatogyrus, Gill. 



t Neritiformis, Desh., is an Anculosa, and is a syu. of A. prcerosa, 

 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 Mdania, as lie has pub- 

 lished it. Species from all countries, without regard to external 

 resemblances, are, in many cases, grouped on its plates indiscrim- 

 inately, I'enderiug the identification of shells by its aid exceedingly 

 difficult. Even several of the species are duplicated in description 

 and illustration in the monographs of Mdania, Jo and Anculotus. 



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 numer- 

 ous cases entirely 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-namcd specimens. 



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

 has elapsed since very many of our Melanians and Unios have Ijeen 

 described, and the large number wliicli have been sent to Europe in 

 scientific cxchanires, European conchologi.sts are still to a great extent 

 ignorant of the most prominent and important specific characters. 



L. F. w. S. IV. 



