Shell with broken, irregular, transverse bars; about %" 

 Anguispira alternata (Say) Barred Leaf Snail 

 {Pyramidula alternata (Say) ) 



222. Umbihcus broad, showing most of the volutions 223. 

 Umbilicus smaller to absent 265. 



223. With somewhat less than five whorls 224. 

 With five to seven whorls 247. 



224. With somewhat less than four whorls 225. 

 With four to four and one'half whorls 232. 



225. Shell relatively smooth; about Vs" 226. 

 Shell definitely transversely striate or ribbed (in direction of growth 



lines); about 1/16" 227. 



226. Aperture oblique, flaring; surface of shell weakly crisscrossed or indent' 



ed; southeastern states 



Helicod-iscus singleyanus (Pilsbry) 

 Whorls increasing more gradually; surface of shell smooth; California 

 Pristiloma shepardae (Hemphill) 



227. Shell with many striae 228. 

 Shell with about twenty to sixty transverse ribs on the last whorl 229. 



228. Shell low, flaring toward the oblique aperture; northeastern and north' 



central states 



Striatura milium (Morse) Millet Seed 

 Shell more globose, increasing more gradually, with more regular aper' 

 ture; more generally distributed 



Punctum minutissimum (Lea) 

 (Punctum pygmaeum (Drap.) ) 



229. Aperture entire 230. 

 Aperture interrupted or excised by parietal wall 231. 



230. With about sixty ribs on last whorl; western states 



Vallonia cyclophorella Sterki 

 With about thirtyfive to forty ribs on the last whorl; east'Central 

 states to Ariz;, and Utah 



Vallonia perspectiva Sterki Vallonia 



231. Lip definitely simple, thin; with about thirty'five to forty transverse ribs; 



northern states westward to Minn. 



Striatura exigua (Stimpson) 

 Lip usually thickened within, at base; with twenty to thirty transverse, 

 thin, erect bars, which may become wavy in dry shells; northern states 

 westward to Michigan 



Playiogyra asteriscus (Morse) Star Snail 



232. Shell discoidal, with fine revolving ridges around the body whorl; usually 



with small teeth back within the aperture; about Vg''; widely dis' 

 tributed 



Helicodiscus parallelus (Say) 

 (Helicodiscus lineatus (Say) ) 

 Not so 233. 



140 



