340 The Molluscan Family Planorbidae 



PLATE 52 



Nidifieation in Planorbidae 



1-3. Helisoma scalare (Jay). Lake Butler, Florida. 

 L Five eggs laid March 13, 1931. 



2. Fourteen eggs laid April 1, 1931. 



3. Ten eggs laid April 2, 1931. 



4-5. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. 



4. Twenty eggs laid June 5, 1933. 



5. Ten eggs laid May 27, 1933. 



6-8. Helisoma eluryi normale Pilsbry. Gainesville, Florida. 



6. Two eggs laid Dec. 25, 1931. 



7. Three eggs laid Dec. 26, 1931. 



8. Four eggs laid Jan. 17, 1932. 



9-11. Helisoma duryi cudiscus Pilsbry. Silver Springs, Florida. 



9. Five eggs laid Dec. 13, 1931. 



10. Nine eggs laid Feb. 6, 1932. 



11. Twelve eggs laid Feb. 10, 1932. 



12. Helisoma duryi normale Pilsbry. Tamiami Trail, 40 miles west of Miami, Florida. 



12. Sixteen eggs laid Jan. 17, 1932. 



13. Helisoma traskii (Lea). Buena Vista Canal, outlet of Kern Lake, California. 



13. Alcoholic specimen wath 50 eggs laid on adult shell. 



14-16. Gyraulus circumstriaius (Tryon). Wainwright Park, Alberta. 



14. Nucleated ovum from ovotestis. 



15. Spermatozoa from o\otestis. Typical (eupyrene) spermatozoa as seen in 



active group. 



16. Eupyrene spermatozoa from the side and from abo\'e. 



Line near figs. 1-13 indicates 1 mm. in length. Line near figs. 14-16 

 indicates 25 microns in length. 



