No. 516] COPULATION AMONG CRAWFISHES 753 



unite sexually as I was careful to observe that the stylets 

 of the male were actually inserted into the annulus of the 

 female. Whether a spermatophore can be transferred 

 under such circumstances is of course still a question. 



The observations described in this paper would lead to 

 the conclusion that the crawfishes have little or no power 

 of sex discrimination. The male " tries " every crawfish 

 which he meets and the instinct of the female is to remain 

 passive under such treatment while another male will at- 

 tempt to escape. The sexes come together as the result 

 of random movements or in the course of the daily travel- 

 ling about in search of food. Holmes reached similar 

 conclusions as a result of his observations on amphipods. 

 Male amphipods, however, would not attempt to copulate 

 with a dead female and in this respect their powers of dis- 

 crimination apparently excel those of the crawfish. 



"Holmes, S. J., " Sex Eecognition among Amphipods," Biol. Bull., Vol. 

 5, 1903, No. 5, pp. 2><i 292. 



