358 The Molluscan Family Planorbidae 



PLATE 61 



Radulae of Helisoma 



See remarks on plate 53. Line at lower right of plate 

 indicates 25 microns in length. 



1. Helisoma occidentale (Cooper). Klamath Lake, Oregon. 



45, center tooth; 1-8, lateral teeth; 9-12, intermediate teeth; 13-23, marginal teeth. 



2. Helisoma subcrenatum (P. P. Carpenter). Cottonwood Pass, Gypsum, Colorado. 



95, center tooth; 1-8, lateral teeth; 9-12, intermediate teeth; 13-20, marginal teeth. 



3. Helisoma oregonense (Tryon). Tooele Co., Utah. 



58, center tooth; 1-8, lateral teeth; 9, 10, intermediate teeth; 11-21, marginal teeth. 



