Classifications of North American Helices. 17 



Shell depressed, thin, highly polished, diaphanous, reddish- 

 yellow; spire little elevated ; suture distinctly impressed; whorls 

 5, slowly increasing, the last broad, rather convex at the base, 

 excavated near the columella ; aperture lunate, with an acute 

 tooth-like fold on the columella; perist. simple, thin. 



Diam. maj. 10, min. 9, alt. 4 mill. 



Habitat. — The mountains between Porto Cabello and Valen- 

 cia, Yenezuela. Rob't Swift ! 



Remarks. — This shell is most nearly allied in form to P. de- 

 2~>ressa Orb., but has less basal callus even than that species, 

 and is readily distinguished from it, especially in being with- 

 out the parietal lamella. In P. Swifti the delicate thinness 

 of the shell, the impressed suture, and absence on the surface 

 generally of the callous thickening which prevails more or less 

 in the other species of the^genus are marked characters. 



P. Swifti is the sole representative of the Family at present 

 known to inhabit South America. Ceres belongs to Mexico, 

 on the borders of the Gulf. Proserpina had hitherto been 

 found only in Cuba, the Isle of Pines, and Jamaica. 



I dedicate the species to my friend Mr. Robert Swift, who 

 called my attention to it, and gave me specimens when I was 

 with him in St. Thomas, "W. I., in November, 1862. 



III. — Remarks on Classifications of North American Helices 

 by European Authors, and especially by H. & A. Adams 

 and Albeks. 



Bt Thomas Bland. 

 Read October 12th, 1863. 



No classification or arrangement of Terrestrial Mollusks, 

 embracing the numerous Genera and Sub-genera proposed by 

 European authors, has at present been attempted or discussed 

 by American Conchologists. 



OCTOBER, 1363. 2 Ann. Lyc. Nat. Hist. Vol. VIII. 



