448 Remarka on Certain Species^ &c. 



In connexion with the subject of variation, I may refer to 

 the great length of time during which species have been per- 

 petuated without alteration. In the Post-pleiocene beds of the 

 Southern States a considerable number of the Helices and other 

 land, and also fresh water species, occur identical with those 

 now living. H. lahyrintltica Say, widely distributed in North 

 America, is said to be an Eocene fossil in England. 



When species have well defined colors, or colored bands, or 

 other ornamentation, uniformly pale individuals are usually 

 noticed as varieties. I have such, in my cabinet, of the follow- 

 ing Helices, viz. : alt&rnata, solitaria, albolahris, ruiultilineata^ 

 perspectiva^ thyroides, interna, profunda, Pennsylxianica, pal- 

 liata, inflecta, tridentata, fallax, and hirsuta. 



In North America there is no species of Helix which, in its 

 normal state, is sinistral, but I may record that I have reversed 

 H. alternata, thyroides, and Mitchelliana ; W. G. Binney has 

 H. fallax, Mr. Isaac Lea H. hirsuta, and Mr. Anthony, I 

 believe, H. injiecta and H. solitaria. 



LIST OF FIGURES ON PLATE IV. 



Fiff. 



