{ THE NAUTILUS. 



P. sterri Voith. (?) Rocky Mountains. 



P. sp. Rocky Mountains. 



P. sterkiana Pilsb. South (and Lower) California. 



P. syngenes Pilsh.^ Arizona. 



Sabg. Leucochila Alb. & Mart. 



P. fallax Say. All east and S. W. to Arizona. 

 P. modica Gld. Ga., Fla. 



Subg. Columella Mart. (Edeiitulina Cless.). 



P. edentula Drp;^ (simplex Old.). All N. A. except southwest. 

 V. alticola Ing. Rocky Mts. 

 var. . Wash., Alaska. 



Subg. Bifidaria Sterki.* 



Sect. . 



P. arizonensis (Gabb) W. G. B. Colo., N. M., Ariz. 



V. saxicola Ckll. Colo. 

 P. corticaria Say. E. of Rockies, except extreme south. 



Sect. Albinula Sterki. 



P. armifera Say. All N. A. 

 P. contracta Say. All N. A. East of Rockies. 

 P. holzingeri Sterki. Ohio to Manitoba, N. M., Kas. 

 V. fordiana Sterki. Kas. 



Sect. Bifidaria s. str. 



P. hordeacea Gabb. Tex. to Ariz. 



P. procera Gld. R. I. to Minn., S. C. to Tex. 



P. hordeacella Pilsb. Fla. to Ariz. 



P. rupicolaSay, S. C. and Fla to La. 



P. servilis Gld. La. ? 



P. (riograndensis Sterki mss.). Hidalgo, Tex. 



Sect. Vertigopsis Ckll. mss. 



P. pilsbryana Sterki. N. M., Ariz. 



P. curvidens Gld.^ All N. A. east of Rockies. 



V. gracilis Sterki. R. I., Ohio, Tenn. 



V. floridana Dull. Fla. 

 P. pentodon Say. All N. A. east of Rockies. 



