Base of shell almost smooth; generally distributed 

 Retinella electrma (Gould) 

 (Vitrea hammoms (Strom)) 



282. With four or five whorls 283. 

 With five and one-half to eight whorls 289. 



283. Umbilicus moderately small 284. 

 Umbilicus tiny; shell about 1/16" to Vs" 286. 



284. Usually with parietal and columellar lamellae; about Vs"' Appalachian 



region 



Pilshryna aurea Baker 

 No teeth within aperture 285. 



285. Shell rib-striate; less than Vs"; western U. S. 



Punctum conspectum (Bland) 

 Shell with weak growth lines; about %"; generally distributed 

 Zomtoides mtidus (Miiller) Yellow Leaf Snail 



286. Eastern and southern species 287. 

 In the Pacific states 288. 



287. With distinct, fine spiral sculpture on the body whorl; about Ys"', 



Florida and Texas 



Guppya gundlachi (Pfeiffer) 

 Spiral sculpture rather obscure; about 1/16"; eastern states 

 Guppya ster\ii (Dall) 



288. Spire flattened; about 1/16" 



Pristiloma nichohoni Baker 

 Spire elevated; about Vg" 



Pristiloma chersinella (Dall) 



289. Lip thickened by a white callus or teeth within 290. 

 Lip simple 297. 



290. No umbilicus; with five and one-half whorls; about %"; Pacific states 



Pristiloma lansingi (Bland) 

 With a small umbilicus; v^-ith five and one-half to eight whorls; about 

 %" to ^2"; eastern and central states to Texas - — • Moss Snails 291. 



291. Umbilicus moderately small, about one-eighth diameter of shell; spire 



rather low 292. 



Umbilicus tiny, sometimes narrowed; spire more elevated in most species 



293. 



292. Aperture toothless; with about five whorls; east-central states 



Ventridens elliotti (Redfield) 

 Usually with small teeth within aperture; usually with about six whorls; 

 northeastern states 



"Ventridens suppressus (Say) 



293. With a light band encircling the body whorl; east of the Mississippi 



Ventndens intertextus (Binney) 

 Shell plain colored 294. 



294. Usually with seven or eight whorls; aperture usually toothed within 295. 

 Usually with six or seven whorls; aperture usually toothless 296. 



145 



