233. Aperture narrowed by three almost evenly spaced teeth; about 1/16'"; 



Okla. and Texas 



Pilshryna tridens Morrison 

 Not so 234. 



234. Body whorl with ribs which continue across the base of the shell 235. 

 Shell smooth or with striae which become obscure on the base of the 



shell 238. 



235. Aperture flaring, with the lip continuing as a thin callus across the pa' 



rietal wall; California 236. 



Aperture more circular; lip not continuing across the parietal wall 237. 



236. Umbilicus very shallow, showing all of the volutions; about y^''; Cali' 



fornia mainland 



Haplotrema caelatum (Ma2;yck) 

 Umbilicus wide and deep; about %"; California and outlying islands 

 Haplotrema duranti (Ncwcomb) 



237. Upper extremity of aperture starting at middle of body whorl; about 



V4"; widely distributed 



Discus croyi\hitei (Newcomb) 

 Upper extremity of aperture starting above the middle of body whorl; 

 Ys^'; southwestern states 



Radiodiscus millecostatus Pilsbry and Ferriss 



238. Aperture flaring, with the lip continuing as a thin callus across the pa' 



rietal wall; shell light horn colored; about V2" to Y/^ 239. 



Lip not forming a callus across the parietal wall; seldom over y^' 240. 



239. About 1/2"; California 



Haplotrema \ecpi (Hemphill) California Wood Snail 

 About y/'; eastern and central states 



Haplotrema concavum (Say) Thin-lipped or White Wood Snail 

 {Circinaria concava (Say) ) 



240. Shell expanding rapidly in size, flaring toward the aperture 241. 

 Shell expanding more evenly 242. 



241. Shell pinkish-brown, with fine transverse grooves; about I/4''; Tenn. to 



Georgia 



Retinella pentadelphia (Pilsbry) 

 Shell whitish, with fine striae; about V4"; northeastern and north-central 

 states 



Retinella hinneyana (Morse) 



242. Body whorl shouldered, with periphery near the top; aperture crescent' 



shaped; shell whitish; about 3/16"; Florida 

 Lacteoluna selenina (Gould) 

 Body whorl more evenly rounded; aperture almost circular 243. 



243. Height definitely over one-half the width; southern states 244. 

 Height about one-half the width; more generally distributed 245. 



244. Whitish; about 3/16"; Florida 



Hojeda inaguensis (Weinland) 



141 



