320 The Molluscan Family Planorbidae 



PLATE 42 



Promenetus 



1,3,7,12. Promenetus exacuous (Say). From Mott Lake, Wainwright Park, Alberta; 

 collected by Dr. Stiles. Received from Canadian National Museum. 



1. Pseudobranch fully expanded. 



3. Penial gland in preputium which has been cut open and the pilasters separated. 



7. Section of penial gland. 



12. Side view of preputium showing penial gland and end of verge passing through 



the diaphragm. 



2,4,5,8-11,13. Promenetus exacuous megas (Dall). From Paul Lake, British Colum- 

 bia; collected by Dr. D. S. Rawson. 



2. Head of animal showing pseudobranch. 



4. Penial gland from above showing trough-like duct leading to muscular ring 



or diaphragm at upper part of preputium. 



5. Penial complex in natural position. 



8. Cross section of ovotestis near middle. 



9. Cross section of ovotestis near posterior end. 



10. Portion of genitalia showing relation.ship of ducts. 



11. Cross section of prostate. An unusual form with split diverticula. 



13. Terminal end of verge showing central exit for sperm canal, small fleshy ap- 



jiendage, and peculiar ring near end. 



6. Promenetus umbilicatcUus (Cockerell). From Wainwright Park, Alberta; collected 

 by Dr. Stiles. Received from Canadian National Museum. 



6. Pseudobranch and jineumostome. 



Line near figure indicates 1 mm. in length. Vertical line bordering 

 figs. 8, 9, and 13 is also for figs. 7, 10, and 11. 



