20 



G. C. Embody. 



Table IX. 



In the case of G. limnaeus, it will be noticed that the shortest period 

 (7 days) between the date of hatching and that of the first moult occurred 

 in water having the lowest as well as in that having next to the highest 

 mean temperature recorded. Again, the longest period (11 days) occurred 

 at a temperature even .4 of a degree higher than that for two of the 

 three cases of the shortest period. This in dicates clearly that a factor 

 other than temperature exerts a strong influence over the first moult. 



Three individuals of the same brood of G. limnaeus and one each 

 of E. gracilis and Hyalella were carried through three or more con- 

 secutive moults from the date of hatching. The data concerning these 

 is shown in the following table. 



Table X. 



