LIFE CYCLE OF SIMOCEPHALUS VETULUS. 7<) 



asexual one was discarded. These two females whose mother 

 was asexual were reared under conditions \\hich \\ere as nearly 

 alike as they could possibly be made and yet have them in i\\o 

 separate vessels, gave rise to diverse offspring. An. equal num- 

 ber of males was placed with each. The history of one was: 

 an empty ephippium, 4 males, 4 sexual and 2 asexual females, 

 an undetermined brood, death. The history of the other was: 

 an empty ephippium, a fertilized egg, a fertilized egg, 3 sexual 

 and 3 asexual females, I sexual and 4 asexual females, death. 

 Each produces an empty ephippium at first, but the former then 

 produces a brood of 4 males, and the latter another ephippium, 

 this time containing a fertilized egg. Both later produce both 

 kinds of females. Several other experiments of this same kind 

 gave similar results. I wish to point out here only one con- 

 clusion based on these experiments, namely, that all afford 

 evidence that the reason for the production of male broods is 

 not the production of ephippial eggs which were not fertilized 

 because of the absence of males, for in these experiments the 

 onset of male brood production has been observed many times 

 in the females which have passed from the sexual state and 

 begun the production of males, in the presence of other males. 



The method of copulation is interesting. This was observed 

 in several instances. The sixth brood of female number 44, of 

 isolation experiment 2, consisted of 8 sexual females and I 

 asexual female. When the first ephippia of these 8 sexual fe- 

 males w r ere in their incipiency I introduced 5 males and watched 

 them almost continuously, removing them when I could not 

 give them attention. When the females were about 6 days old 

 the ephippia were well developed and the ephippial eggs seemed 

 to be ready to be extruded into the brood pouch. It was at this 

 time that the monotony of proceeding was relieved. On being 

 placed in the vessel with the females the males at once became 

 intensely excited. This lasted nearly an hour. After several 

 abortive attempts at pairing one pair mated. The male opened 

 his carapace slightly and clasped the antero-ventral margin of 

 one side of that of the female. He then bent his abdomen ven- 

 trad, so that it extended between the ventral margins of the 

 female's carapace, ventral to her posterior appendages. In 



