ass APPENDIX. 



but not prominently wrinkled, and grooved transversely ; 

 aperture moderate ; labrum reflected, with a slightly pro- 

 jecting dentiform callus near the base on the inner edge ; 

 labium with 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. j)rofunda nob. but may be distinguished by its 

 smaller size and armed labium. Its aperture also is much 

 less dilated than that oHh^profunda. PI. 15, fig. 4. 



H. 2ierspectiva nob. is common in the North-west Ter- 

 ritory, it varies in being smaller, and in the circumstance 

 of the labrum embracing a somewhat smaller proportion 

 of the penultimate volution. 



H. arborea nob. common in this territory. 



H. chersina nob. A variety of this species is not un- 

 common 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 and albolabris nob. On our return home- 

 ward these two species were not found until we arrived in 

 the secondary country towards the eastern extremity of 

 Lake Superior. 



H. thyroidus nob. Falls of Niagara. 



H. ligera nob. North-west Territory. 



VITRINA, Draparn. 



V. pellucida of authors. This shell was first found near 

 Coldwater Lake in latitude 48|° north, under stones, fallen 



