130 
the body whorl with dull greenish and pale oehraeeous ; and the 
chesnut-brown color of the interior of the shell, combined with ite 
large dimensions, distinguish this species from all others yet dis- 
covered in this country. PI. 15, fig. 10.* 
Lymneus emarginatus, nob., from Lake Namakan, north of 
Lake Superior ; collected by Dr. Bigsby. 
Lymneus elongates, nob. Bainy Lake and Seine river. Dr. 
Bigsby. 
Lymneus desidiosus, nob. Falls of Niagara. 
Physa heterostropha, nob. North-west Territory. 
Valvata sincera. — Shell subglobose-conic ; whorls nearly 
four, accurately rounded, finely and regularly wrinkled across } 
aperture not interrupted by the penultimate whorl nor appressed 
to it, but merely in contact with it, the labrum not diminished in 
thickness at the point of contact ; umbilicus large, exhibiting the 
volutions. 
Breadth less than one-fifth of an inch. Inhabits North-west 
Territory. 
For this species I am indebted to Dr. Bigsby. It is very similar 
to the tricarinata, nobis, but is destitute of carinated lines, and 
the umbilicus is rather larger; it differs from the ohtusa of 
Europe, also, in the much greater magnitude of the umbilicus. 
PI. 15, fig. 11.* 
Paludina limosa, nob. North-west Territory. 
Ampularia depressa. — Shell ventricose, subglobular, obso- 
^ letely banded with obscure green ; whorls four, slightly wrinkled ; 
body whorl more prominent above, somewhat flattened towards the 
suture, of a pale olivaceous color, which is almost concealed by 
numerous, unequal, longitudinal and transverse greenish and brown- 
ish lines ; spire very much depressed ; aperture suboval, within 
somewhat glaucous, on the margin exhibiting the bands distinctly : 
labrum simple, as much rounded above as below ; umbilicus small, 
nearly closed. 
Gireatest width one inch and nine-twentieths. Total length one 
inch and a half. Length of the aperture one and one fifth of an 
inch nearly. Inhabits East Florida. 
During an excursion to East Florida, in company with Messrs. 
Maclure, Old and T. Peale, I obtained a single dead and imperfect 
* [Plate 74 of this reprint. ^ — E d.] 
