296 The Molluscan Family Planorbidae 



PLATE 30 



Helisonia 



1-9. Helisoma plcxatum (Ingersoll). Collected by J. Henderson. 



1. Penial complex with penial gland duct uncoiled. From Columbine Lake, 



Colorado. 



2. Penial complex with vergic sac cut open to show form of verge. 



3. Penial comiilex in section to show form of gland. From Columbine Lake, 



Colorado. 



4. Genitalia dissected and organs separated. From Smartweed Lake, Colorado. 



5. Cross section of penial gland. From Lower Los Lagos, near Smartweed Lake. 

 6-8. Section of vergic sac showing form of \erge in different individuals. From 



Teton River, north of Rexburg, Idaho. 

 9. Form of verge in a specimen from Smartweed Lake, Colorado. 



10-19. Helisoma subcrcnalum (P. P. Carpenter). From one mile west of Devon, 

 Montana; collected by J. Henderson. 



10. Penial complex showing short penial gland duct in immature specimen. 



11. Section of penial gland. 



12. Cross section of prostate about midway of its length. 



13. Section through penial complex showing verge and penial gland. 



14. Albumen gland from below. 



15. Genitalia dissected and organs separated. 



16. Head showing pseudobranch, pneumostome, and rectum. 



17. Penial complex with penial gland duct uncoiled. 



18. Penial complex in section showing form of penial gland and verge. 



19. Penial complex with vergic sac cut open to show verge. Figures 17-19 are 



from specimens collected at Cottonwood Pass, near Gypsum, Colorado. 



Line near figure indicates 1 mm. in length 



