THE NAUTILUS. 41 



!^j>ecies of ValviitJe possessing an elevated spire ; hence this feature 

 alone has but slight value, and I have always referred it to Valvata 

 as a subgenus, before anything was known of its anatomy. The 

 said character is not generic, even snbgenerio, and I must remark 

 that in the same species, chiefly in Cyclostomidse (Ostodes liberatus, 

 Mousson, for instance), the last whorl is more or less solute. 



The two New Caledonia fluviatile shells, Heterocychis Perroqvini 

 and Valvata Petiti, were originally generically separated by Mi-. 

 Crosse on account of this feature occurring in the former oidy, 

 although the other ones are nearly the same in the two, namely that 

 of the peristome being more or less expanded or reflected in both. 

 This very striking particular alone should justify the distinctness of 

 Heterocychis from Lyogyrus or Valvata; but nothing of the anatomy 

 being known we are not authorized to declare it generically separ- 

 able, notwithstanding the locality, the two shells being restricted to 

 the lakes of Southern New Caledonia. 



In regard to Thomsonia and the only species, carinifera, Anc. (= 

 Physa (" Paludina ") scalaris, Jay), related to it, I must say, at finst, 

 that the subgeueric name proposed is Thomsonia, not Thompsonia, 

 and should the latter be already pi'eoccupied in another branch of 

 Natural History, the name proposed would stand, being at least as 

 much different from Thompsonia, as Helix Raimondii, Phil., is from 

 Helix Remondi, Tryon, Helix Raymondi, iVIoq., etc. I must add 

 that I am not aware that even Thomsonia is not also preoccupied in 

 Zoology, for nobody is universal, and although having published on 

 Entomology as well as Conchology, I have not particularly studied 

 every part of Natural History ; this should, I think, be a sufficient 

 apology for giving such a name. 



My excuse for changing the name of Helix Harfordiana, W. G 

 Binney (not J. G. Cooper) to commutanda, is that my paper was 

 sent for printing when Tryon's name was still unpul)lished or rather 

 when his work had not yet reached Europe. Similar facts com- 

 monly happen, and authors are, in this case, fairly excusable. 



I will remark upon another observation in Mr. Pilsbry's article : 

 " Although American Conchologists have not been finding ' new 

 " species ' of fresh water shells in the Eastern States for the last 

 " decade or two. Continental writers, with delicious coolness, con- 

 '-'tinue to describe 'novelties' from Massachusetts, Maryland and 

 " other well-known localities." 



