220 AMERICAN JOURNAL 



In 1838 Mr. Lea described and figured a shell from the Ohio 

 River, under the name of MeJania Cmcinnatiensis. I have spe- 

 cimens from the Holston Riv^r that exactly conform to the terms 

 of his description, and among them are specimens that might he 

 substituted for the specimen that was the original of his figure. 

 At a later date Mr. Lea described the mature shell as Anculosa 

 tintinnabulum. In the series of specimens by which I unite 

 Cincinnatiensis and tintinnabuhan,* the smallest is less than 

 0*08 inches in diameter, being about half as large as the origi- 

 nal '■''Mel. Cincinnatiensis.'' The series progresses through a 

 large number of individual specimens to the largest adult tin- 

 tinnahuluin. I feel assured that identification was never more 

 complete. 



Mr. Tryon in his synonymy and elsewhere expresses the opin- 

 ion that Mel. Cincinnatiensis, Lea, is the young of Anculosa 

 prcerosa, Say. Some of the varieties (so called) of Anculosa 

 p)'cerosa, have bicarinate young, but their forms are such that 

 when of the dimensions of Mr. Lea's typical Cincinnatiensis 

 (diameter 0*16 inch) they do not exactly, but onl;y approximately/, 

 correspond thereto, and therefore must yield to the claims of 

 tintinnabulum. 



Having conclusively ascertained that the young of Anculosa 

 tintinnabulum are bicarinate and exactly correspond to Mr. Lea's 

 figure of Mel. Cincinnatiensis, it remains now to compare these 

 young specimens with the young o^ Anculosa subglobosa of cor- 

 responding size ; if there is perfect agreement, Mr. Tryon's 

 synonymy of suhglobosa (which includes tintinnabulum) may be 

 allowed to pass unquestioned. If there are very conspicuous and 

 constant differences it seems to me that these, considered in con- 

 nection with the constant differences I observe in the adults, im- 

 ply they are distinct species. INIy specimens of A. subglobosa 

 embrace numerous specimens from \ inch diameter to the full 

 grown adult, none of which are carinate, nor can I find any evi- 

 dence by which I might identify subglobosa with tintinnabulum. 



TO. Anculosa prcerosa, Say. There are clearly as many as ten 

 or twelve well marked and constant varieties (?) referable to this 

 species. The differences in some of these are remarkable, and 

 are not confined to the adult specimens. Of some of these va- 

 rieties I have very small specimens. In one variety carintB are 

 scarcely discernible in the smallest specimens. In others there 

 are traces of carina upon shells of nearly or quite J inch in 



* With reference to my position ia this matter, I will remark that Mr. 

 U. P. James, of Cincinnati, finds A. tintinnabulum in the Ohio River. I 

 have a single specimen from the Ohio River, labeled "prcerosa " by Mr. 

 Wheatley. 



