HELIX. 47 



I have differed from the opinion of H. Mitchelliana 

 expressed on vol. ii. p. 109. My reasons for so doing will 

 be found under that species. The outline figures repre- 

 senting it must, therefore, not be confounded with the 

 central figures. 



H. clausa Say has not been correctly described nor 

 figured by any author but Say and Binney, until the last 

 year, when it was correctly treated by Bland. DeKay 

 has, indeed, described it as distinct from Pennsylvanica, 

 but his figure is little characteristic, and his notes of its 

 geographical distribution are incorrect. Reeve's figure 

 referred to in the Synonymy may, perhaps, represent this 

 species. In the text he confounds it with Pennsylvanica. 



In the second edition of Chemnitz, Pfeiffer appears to 

 have described and figured it, though he doubtfully refers 

 it to Mitchelliana. 



Say's original specimen is still preserved in the Acad- 

 emy of Natural Sciences. 



The species occurs fossil in the Postpleiocene, and 

 is found in the greatest profusion in some portions of 

 the South, in what appears to be a semi-fossil condi- 

 tion. I have seen fresh specimens from Ohio, Indiana, 

 Illinois, Kentucky (Kennicott), Missouri, Wisconsin, Mis- 

 sissippi, Alabama (Showalter). 



The rounded, smoother variety, figured in the Boston 

 Journal, may be distinguished from the foil owing species 

 principally by its perforation. There are forms, also, 

 which nearly approach H. bucculenta. 



HELIX MITCHELLIANA LEA. 

 PLATE IV. Outline figures. 



T. superne obtuso-conica, inferne inflata, longitudinaliter et sub- 

 tiliter striata, cornea, diaphana, imperforata, anfr. 5 ; apertura sub- 

 rotundata ; labro reflexo ; columella lasvi. 



Shell above obtusely conical, below inflated, longitudinally and 



