od 
W. Stimpson on the so-called Melanians of N. America. 41 
Art. V.—On the structural characters of the so-called Melanians of 
North America; by Dr. WM. Stimpson. 
+ In the very interesting series of lectures on the Mollusca, by 
Dr. P. P. Carpenter, recently published by the Smithsonian Insti- 
tution, under the heading of ‘Fam. Melaniide” the following 
pemeee occurs: ‘It is much to be regretted that American col- 
ectors, who have not been slow to avail themselves of the exu- 
berant riches lying at their feet, which are so acceptable to 
European naturalists, have so generally entirely neglected the 
preservation and study of the opercula; and that so many points 
in the physiology and habits of these easily-observed animals 
have not yet been made known.” 
There is only too much of truth in this remark. Not only 
“American collectors,” but American naturalists, have been 
hitherto content with describing, from the shell alone, the multi- 
tudes of species of Melanians which swarm in our fresh-water 
streams and lakes, without any attempt to acquire a knowledge 
of the structure of these animals, or to determine the relations of 
while studying the characters of our North American Amunico! 
and [ will present here the results of the few observations which 
* Smithsonian Report for 1860, p. 206. 
* The following Coes to ‘pri dete of this species: Paludina dissimilis Say, 
me igrescens Conrad, A. dentata Couth., A. carinata DeKay, and A. trivit- 
tata DeKay. All these forms are found living together in the Potomac above “ Lit- 
tle Falls,” and the exact similarity of the soft parts of the animal, in pattern of 
Coloration, etc., in all of them, leads me to regard them as specifically identical. 
Ax. Jour. Sct.—Seconp Series, Vor. XXXVIII, No. 112.—Juxy, 1864. 
6 
