460 



MICHIGAN SURVEY, 1905. 



Fig. 2. Genitalia of P. albclabris (Simpson). 



1. Atrium. . 6. Vas deferens. 11. Hermapliroditic duct. 



2. Penis. 7. Free oviduct. 12. Hcrmapiirodtic gland. 



3. Prepuce. 8. Uterus.i 13. Penis retractor. 



4. Vagina. 9. Spermatic duct. 14. Albumen gland. 



5. Spermatheca. 10. Talon. 



Genus POLYGYRA Say. 



Shell helicoid, varying from globose or depressed-globose to lens-shaped or 

 piano rboid; the periphery carinated or rounded; umbilicus either open or 

 closed. Surface striated or hirsute; corneous, yellow or brown, generally 

 unicolored, but sometimes wdth many bands, the most constant being supra- 

 peripheral, the others when present being wholly indefinite in number and 

 position. Lip well refiexed; aperture typically obstructed by three teeth; 

 one parietal, two upon the lip ; but any or all teeth often wanting. 



Animal heliciform, the man- 

 tle sub-central, foot rather long 

 and narrow. No pedal grooves. 

 Surface rather coarsely and ir- 

 regularly granulated, the gran- 

 ulations finer posteriorly; back 

 with a .pair of indistinct grooves 

 extending from mantle to facial 

 area; sides of foot, and sides of 

 top of tail without any distinct, 

 oblique or longitudinal lines, 



Fig. 3. Animal of P. albolabris. 



(Binney.) 



irregularly granulated; tail rounded above, obtuse behind. 



