OF NORTH AMERICA. 



515 



PLATE X. 



Figure A. Genitalia of Lymnaa stagnalis appressa SAY. The organs are sepa- 

 rated from each other to show their form. AL, albuminiparous 

 gland; A 1 , first accessory albuminiparous gland; A 2 , second 

 accessory albuminiparous gland; CM, columellar muscle; N, 

 penis nerve; O, ovotestis; OS, ovisperm duct; OV, oviduct; 

 OV 1 , free portion of oviduct; P, penis; PM 1 , posterior pro- 

 tractor muscle of penis-sac; PM 2 , anterior protractor muscles 

 of penis-sac; PR, prostate; PR 1 , bulb-shaped portion of pros- 

 tate; PRM, penis retractor muscle; PS, penis-sac; RM, re- 

 tractor muscles of penis-sac ; S, receptaculum seminis, or 

 spermatheca; SD, its duct; U, uterine portion of oviduct; V, 

 vagina; VD, vas deferens; VD 1 , vas deferens to prostate; 2, 

 penis-sac showing attachment of retracting muscles. (Dissec- 

 tion from animal killed in August.) 



B. Genitalia of Pseudosuccinea columella (SAY). (Animals killed in 



May and August.) 



C. Genitalia of Radix auricularia (LINNE). 1, side view of prostate. 



(Animal killed in April.) 



D. Genitalia of Bulimnea mcgasoma (SAY). (Animals killed in Sep- 



tember.) 



PLATE XI. 



GENITALIA. 



Figure A. Galba cubensis (PFR.). (Animals killed in April.) 



B. Galba umbilicata (ADAMS). 1, penis of one example. 



C. Galba obrussa (SAY). (Killed in August.) 



D. Galba parva (LEA). 



E. Galba palustris (MULLER). (Killed in August.) 



F. Acella haldemani ((DESK.) BINNEY.) 1, side view of prostate. 



(Killed in October.) 



PLATE XII. 



GENITALIA. 



Figure A. Galba reflexa (SAY). (Killed in September). A, side view of 

 prostate. 



B. Galba catascopium (SAY). (Killed in August.) 



C. Prostate of Galba obrussa (SAY). 1, from above; 2, from side. 



D. Lymnaa stagnalis appressa SAY. Variation in penis retractor 



muscles. 1, with penis retractor 'split into two branches ; 2, with 

 unbroken retractor; N, penis nerve; P, penis retractor; S, penis- 

 sac retractor. 



E. Galba reflexa (SAY). Prostate. 



F. Radix auricularia (LINNE). Retractor muscles of male organs. 1, 



penis retractor; 2, minor, and 3, major branch of penis-sac 

 retractor. 



G. Galba emarginata (SAY). (Killed in September.) 

 H. Galba emarginata angulata (Sows.). 



