TABLE 18 



Showing number of male- and female-producers in the progeny of two sister individuals 

 of Hydatina senta, one line being reared at a temperature of 18° to 23° C, the other 

 at 7° to U° C. 



18° TO 23° C. 



NO. OP GBNEUA- 

 TION 



1 Oct. 8 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 



16. 

 17. 

 18. 

 19. 

 20. 



21. 



22. 

 23. 



24. 

 25. 

 26. 

 27. 

 28. 

 29. 

 30. 

 31. 

 32. 



DATE OP 

 PIRST 

 YOUNG 



NO. OF 



10 

 12 

 14 

 15 

 17 

 18 

 20 

 21 

 23 

 25 

 27 

 28 

 30 

 31 



Nov. 1 : 



2 

 3 

 5 



8 

 10 

 12! 

 12 I 

 13 

 15 ' 

 18 

 18 I 

 21 ' 

 23 

 26 

 29 

 3 

 5 

 7 

 10 

 13 



Dec. 



37 

 11 

 13 

 2 

 

 

 

 10 

 

 4 

 9 

 2 

 31 

 6 

 

 8 

 1 

 

 4 

 12 

 2 

 2 

 2 

 

 

 1 

 2 

 5 

 1 

 1 

 2 

 

 

 1 

 ] 

 



NO. OF 



9 9 



2 

 34 

 32 

 12 

 31 

 35 

 48 



4 

 17 

 27 

 34 

 17 

 13 

 32 

 14 

 20 

 23 

 43 

 33 

 14 



5 



9 

 11 

 19 

 32 

 31 





 13 

 20 

 28 

 23 

 37 

 30 

 20 

 21 



3* 



7° TO 14' C 



NO. OF GEN- 

 ERATION 



Total 



Per cent of cf 9 



170 

 17.7 



787 



10 

 11 



12 



13 



14 



DATE OF 

 FIRST 

 YOUNG 



NO. OF 



cf 9 



Oct. 8 



12 



16 



20 



25 



30 



30 



Nov. 6 



6 



6 



6 



12 



12 



16 



16 



19 



24 



24 



30 



30 



Dec. 4 



4 



9 



9 



22 



10 



15 



24 



5 



11 



14 



13 



9 



16 



5 



7 



9 



7 



19 



25 



16 



27 



30 



20 



6 



33 



7 



14 



364 

 45.6 



NO. OF 



99 



11 

 32 

 17 

 22 

 30 

 24 

 19 



2 

 27 

 28 

 19 

 26 

 21 

 20 



7 

 17 

 20 

 16 

 15 

 23 

 29 



1 



4* 



3* 



433 



*Remainder of family not recorded. 



