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inhabiting the United States » 491 



parts of Pennsylvania and Virginia and the States bor- 

 dering upon the Ohio river. It is very abundant in the 

 neighborhood of Cincinnati, Ohio. 



Remarks. The first description of this shell was by 

 Mr. Say^ in the Journal of the Academy of Natural 

 Sciences of Philadelphia, in January 1821. Early in 

 1822 it was indicated by Ferussac in his Tableau Syste- 

 matique No. 94, as Helix KnoxviUina^ as was afterwards 

 shown, when the explanation of the supplementary plates 

 of his work was pubHshed, in which the figure of this 

 species is referred to as Helix Knoxvillina of his Tab- 

 leau, and as Helix elcvdta of Say. Mr. Say's descrip- 

 tion having been published a year before the name of 

 Ferussac, which was unaccompanied with specific charac- 

 ters to enable the reader to identify it, should give the 

 name first imposed, the precedence, and I therefore retain 

 it. M. D'Orbigny, in his Synopsis of the land and fresh 

 water shells of South America, published in Guerin's 

 Magazin de Zoologie for 1835, has applied the same 

 name to one of the species described by him. He Avas 

 doubtless ignorant that it had been pre-occupied, and will 

 of course replace it by another, when the fact is known 

 to him. 



This is a rather thick and heavy shell. It resembles 

 H. Pennsylvanica in general aspect, but is larger, has one 

 more whorl, and is a coarser shell. .The tooth on the 

 pillar lip, which is wanting in the other, will always ena- 

 ble one to distino-uish the mature shells ; but the young 



O 



resemble each other so nearly that it is difficult to discover 

 a difference. The variations of the species are small — the 

 greater or less elevation of the spire, is the common cause 

 of the differences. 



In captivity, it burrows much under the surface of the 



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