300 The Molluscan Family Planorbidae 



PLATE 32 



Helisoma 



1-7. Helisoma tenue californiense F. C. Baker. From pools from artesian wells, near 

 Shandon, California; collected by Dr. G. D. Hanna. 



1. Genitalia dissected and organs separated. 



2. Penial complex cut open to show verge. 



3. Penial complex with vergic sac at summit of preputium. 



4. Pseudobranch, pneumostome, and rectum. 



5. Penial gland viewed from the outside. 



6. Section of prostate and uterus. 



7. Penial complex with penial gland duct uncoiled. From Prospect Park, Red- 



lands, California; collected by Dr. S. S. Berry. 



8. Helisoma subcrenatum (P. P. Carpenter). Variety. From Pass Lake, Fidalgo 

 Island, Puget Sound, Washington; collected by J. Henderson. 



8. Penial complex with preiiutium pushed upward. 



9,10. Helisoma occiclentale (Cooper). From Wacos Bay, Klamath Lake, Oregon; 

 collected by J. Hendenson. 



9. Position of verge in vergic sac. 



10. Penial complex with preputium pushed ujjward. 



11-17. Helisoma traskii (Lea). From slough near Kern River, three miles northeast 

 of Bakersfield, California; collected by L. G. Ingles. 



11. Penial complex cut open to show form of penial gland. 



12. Cross section through prostate, uterus, and nidamental gland. 



13. Section through penial gland. 



14. Penial complex in normal position with penial sland duct uncoiled. 



15. Pseudobranch, pneumostome, and rectum. 



16. Bifid tentacle. 



17. Genitalia dissected and organs separated. 



Line near figure indicates 1 mm. in length 



