THE NAUTILUS. 41 
species of Valvatze 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 subgeneric, and I must remark 
that in the same species, chiefly in Cyclostomidz (Ostodes liberatus, 
Mousson, for instance), the last whorl is more or less solute. 
The two New Caledonia fluviatile shells, Heterocyclus Perroquini 
and Valvata Petiti, were originally generically separated by Mr. 
Crosse on account of this feature occurring in the former only, 
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 
Heterocyclus 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 first, 
that the subgeneric name proposed is Thomsonia, not Thompsonia, 
and should the latter be already preoccupied 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, Mogq., ete. I must add 
that I am not aware that even Thomsonia is not also preoccupied in 
Zodlogy, 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sent for printing when Tryon’s name was still unpublished or rather 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.” 
