356 The Molluscan Family Planorhidae 



PLATE 60 



Radulae of Helisoma 



See remarks on plate 53. Line at lower rig;ht of plate indicates 

 25 microns in length. 



L Helisoma subcrciialum (P. P. Carpenter). Variety. Lost Lake, Paget Sound, 

 Washington. 

 73, center tooth; 1-7, lateral teeth; 12, 13, intermediate teeth; 15-20, marginal 

 teeth. 



2. Helisoma subcrenatum (P. P. Carpenter). Variety. Lost Lake, Puget Sound, Wash- 



ington. 

 88, abnormal center tooth; 5. lateral tooth with bicuspid entocone. 



3. Helisoma subcrenatum (P. P. Carpenter). Skagit Co., Washington. 



90, center tooth; 1, 7. lateral teeth; 12, intermediate tooth; 17, 20, marginal teeth. 



4. Helisoma traskii (Lea). Outlet of Kern Lake, California. 



82nd row, 9, intermediate tooth; 10. 11, marginal teeth. 



5. Helisoma traskii (Lea). Outlet of Kern Lake, California. 



90, center tooth; 1-9, lateral teeth; 10, 11, intermediate teeth; 12-22, marginal 

 teeth. 



6. Helisoma traskii (Lea). Outlet of Kern Lake, California. 



80th row, 9, intermediate tooth; 10, first marginal tooth. 



7. Helisoma horni (Tryon). Paul Lake, British Columbia. 



60, center tooth; 1-9, lateral teeth; 10-14, intermediate teeth; 15-32, marginal 

 teeth. 4, fourth tooth in another row. 



