274 The Molluscan Family Planorbidae 



PLATE 19 



Gyi'aulus 



1-3. Gyraidus co7ivexiusculus (Hutton). From Calcutta, India; from Dr. B. Prashad. 



1. Cross section of one diverticulum of prostate showing separate canals for 



prostate duct and sperm duct. 



2. Genitalia dissected and organs separated. 



3. Pseudobranch and pneumostome. 



4-9. Gyraulus latestomus F. C. Baker. From Cedar Lake, Algonquin Park, Ontario, 

 Canada; collected by A. LaRocque. 



4. Distal end of genitalia from left side. 



5. Albumen gland from below, showing loop of intestine. 



6. Penial complex. 



7. Cross section of one diverticulum of prostate. 



8. Anterior end of body showing pseudobranch and ])neumostome. 



9. Genitalia dissected and the organs separated. 



Line near figure indicates 1 mm. in length. Figures 1 and 7 

 are greatly enlarged. 



