COXJUGATIOX IX THE CRAYFISH, CAMBARUS AFFIXIS 259 
We have observed conjugation in C. affinis, C. virilis, C. clarkii, 
C. immunis, C. bartonii and A. E. Ortman in C. obscurus;^ and 
as far as observed the process is like that in C. affinis, though the 
details have not been studied. 
^Mien some seven male and only one or two female C. virilis 
were kept with about two hundred C. affinis, the individuals of 
the former species found one another and the female C. virilis 
was conjugating with a male C. virilis. 
While the males thus select the females of the same species, 
as far as these observations show anything, it is yet possible for 
the conjugating reflexes of the male to be brought into action 
toward a female of the other species. Thus when a male C. 
affinis from which the first and second stylets of the left side had 
been cut off was about to seize a female C. affinis in the corner of 
a dish, the female was removed and a female C. virilis put in its 
place. The male drew back, stood as if looking at the new female, 
went to the other end of dish, and in a few minutes returned 
to face the female and rest his long antennae upon her thorax for 
a few minutes, then suddenly seizing her tried to turn her. In 
a few minutes the male was mounted upon the passive female and 
holding her chelae, but not her other legs. The male then made 
attempts to get more and more of the claws of the female in his 
claws, at times holding most of them, and meanwhile made quick 
use of the third maxillipeds to feel over the ventral face of the 
thorax of the female, The claw of the s.econd leg was also passed 
over the median part of the thorax of the female. But the male 
then desisted and the female remained passive, turned first on 
the side and then to the ventral face, but still held by the right 
claw of the male fast to her right claw and by the left claw of 
the male fast to her rostrum. Ten minutes later the male was 
mounted again and held all the chelate legs of the female in 
his claws, except one on the left. Half an hour later the male 
had crossed the left fifth leg anterior to the stylets which remained 
on the right side, having been cut off from the left side. Yet 
* Pearse has studied the conjugation in C. blandingii, C. diogenes, and C. virilis; 
Am. Nat., Dec. 1909. 
