31 



labrum reflected, with a slightly projecting dentiform callus near 

 the base on the inner edge ; labium ^vith an oblique tooth on the 

 middle ; umbilicus rather large, profound, exhibiting all the 

 volutions. 



Breadth rather more than seven-tenths of an inch. This shell 

 inhabits the State of New York. It is closely allied to H. pro- 

 funda, Jfoh., but may be distinguished by its smaller size and 

 armed labium. Its aperture also is much more dilated than that 

 of the profunda, PI. 15, f. 4. 



H. PERSPECTIVA, Nob. — Is common in the North-west Terri- 

 tory ; it varies in being smaller, and in the circumstance of the 

 labrum embracing a somewhat smaller portion of the penultimate 

 volution. 



H. ARBOREA, Nob. — Common in this Territory. 



H. CHERSINA, Nob. — A variety of this species is not uncommon 

 in the North-west Territory. It differs in the greater rotundity 

 of the upper part of each whorl, and in the somewhat less rounded 

 or more flattened figure of the labrum. It may, however, prove 

 to be a distinct species, when many specimens of chersina can be 

 had to compare with it. 



H. Alternata, Nob. and H. albolabris. — On our return 

 homewards, these two species were not found until we arrived in 

 the secondary country towards the eastern extremity of Lake 

 Superior. 



H. THYROTDTTS, NoB. — Falls of Niagara. 



H. LIGERA, Nob. — North-west Territory. 



Vitrina pellucida of Authors. — This shell was first found 

 near Cold water Lake in latitude 48 f north, under stones, fallen 

 timber, &c. It afterwards frequently occurred in similar situa- 

 tions, until we approached Lake Superior, when it was no more 

 seen. Like its congeners, the inhabitant is much too large to 

 retract within the shell, and a great portion of the body is there- 

 fore constantly exposed. No species of this genus has been 

 hitherto found in this country ; the discovery of this shell is 

 therefore the more interesting. The specimens which we collected 

 do not appear to differ in any respect from those of Europe. 



BuLiMUS lubricus of Authors. — The species occurred under 

 stones, &c., on the shores and islands of Lake Winnepeck and 

 Lake of the Woods. It is altogether similar to the European 



