V. 



CATALOGUE OF SHELLS, WITH DESCRIPTIONS OF 



NEW SPECIES. 



BY DR. A. A. GOULD. 



Helix albolabris, Say. Northern shore, Michipicotin. 



" tridentata, Say. Niagara, Mackinaw. 



" thyroidus, Say. Niagara, Mackinaw. 



" alternata, Say. Niagara, Mackinaw. 



" palliata, Say. Niagara. 



" rnonodon, Raclcett. Niagara, Mackinaw. 



" perspectiva, Say. Niagara, Mackinaw. 



" striatella, Anthony. Fort William, Cape Gourganne, N. E. of St. Ignace. 



" concava, Say. Niagara. 



" arborea, Say. Mackinaw, Fort William, Cape Gourganne, St. Ignace. 



" electrina, Gould. Cape Gourganne. 



" chersina, Say. Michipicotin, Cape Gourganne. 

 1 Vitrina limpida, Gould. Cape Gourganne. 

 Succinea ovalis, Gould. Fort William. 



obliqua, Say. Niagara, Northern Coast. 

 " avara, Say. Niagara. 

 Physa heterostropha, Say. Black River, Pie Island, Fort William. 



i VITRINA LIMPIDA, Gould (V. pelludda, Say, in Long's Expedition. II. 258.) Having 

 made a critical comparison of our Vitrina with the V. pelludda of Europe, with which 

 species it has hitherto been regarded as identical, I am induced to believe that they are 

 different species. The American shell is more globose ; the plane of the aperture is 

 more oblique, and the basal portion of the lip sweeps round from the columella in a 

 rapidly curving arc, instead of stretching off almost horizontally ; indeed the whole 

 aperture is more nearly circular. These differences become quite obvious when the 

 shell is greatly magnified. The color of the European shell is always more or less 

 green or yellow, whereas the American specimens are colorless, and decidedly more 

 fragile. In size, they are about one fourth smaller than the foreign ones, and have, at 

 least, half a whorl less in the spire. It is indeed more nearly like V. subr/tobosa, Mich, 

 which, however, has a much more elevated spire, and its basal face much more inflated. 



