& AMERICAN JOURNAL 



Wm. M. Gabb, of his valuable Conchological collection, compris- 

 ing from 4000 to 5000 species. 



The following papers were offered for publication, and referred 

 to committees : 



"Notices and Reviews of new Conchological Works." By 

 Geo. W. Tryon, Jr. 



" Description of a new species of Cephalopod from the South 

 Pacific. By Wm. M. Gabb. 



Mr. Tryon read extracts from a letter received from Dr. 

 James Lewis, of Mohawk, New York, as follows : 



Notes on certain Fresh-water Shells, observed in the vicinity of 

 Mohawk, N. Y. By James Lewis, Mohawk, N. Y. 



" I have ceased to expect species to present an invariable 

 character, for I find that they vary considerably in contiguous lo- 

 cations. An instance is afforded in Bythinella obtusa, which, in 

 the river here, grows large, the soft parts, as seen through the 

 shell, being orange ; smaller in the canal, the soft parts less 

 usually orange, more frequently gray. I scarcely need mention 

 Melantho rufa, the shells of which from canal and river are quite 

 as conspicuously varied ; and 31. Integra, the shells of which in 

 the canal are often curiously varied from the normal form. 



"The variations of (Joniobasis Virginica, which in James River, 

 Va., is almost a pupoid, or more nearly a cylindrical shell, be- 

 come conspicuous when compared with shells of the Hudson, and 

 the Erie Canal. Yet their identity is by no means questionable. 



" It is a grave fault with collectors that they do not closely 

 study the psychical characters of species. I mean by this, that 

 which relates to their vitality, and the influences which, acting 

 upon the susceptibilities of organic beings, modifies their rela- 

 tions to their surroundings by such slight variations of external 

 or internal characters, as in some instances leads to the hasty 

 conclusion, that a number of individuals, varying from the forms 

 we have usually seen as the external exponents of the same spe- 

 cies, must be different species. I am in a measure influenced by 

 ideas similar to those entertained by Darwin ; and when his 

 views became known, I had already anticipated some of them 

 from the little I had observed in nature. 



" I am aware that some of our shells are very perplexing. 

 Take the following, viz : Melantho, Physa, Goniobasis, Lym- 

 noza, Succinea. I do not know that it is possible to make clear 

 the obscurities that these things are involved in. Certainly I 

 can in a measure excuse the sweeping treatment of Melantho, 

 indulged in by some authors, in view of the fact that there are 



