284 THE AMEBIC AX XATURALIST [Vol. XL VI 



barus affinis until the individual has reached a third stage 

 after leaving the egg. 



The method of sperm transfer in C. affinis, and that 

 of C. b. b. as well, is as follows : 



The male everts the bent, nozzle-like papilla? at the mouth of the 

 vasa deferentia and through them discharges sperm into an actual 

 tube that passes down each of the first two abdominal appendages or 

 stylets. Both first and second pairs of stylets are locked together by a 

 peg and groove contrivance. The sperm thus passes through a closed 

 tube from the vasa deferentia into the annulus ventralis without com- 

 ing into contact with the water. Copulation lasts from two to ten 

 hours and may be repeated by either animal with some other (3, 4). 



In a previous paper, I pointed out (21) that the males 

 do not distinguish the females and that males " repeat- 

 edly grasp other males, and sometimes, in spite of their 

 frantic struggles turn them over and attempt to copulate 

 with them." The crayfish is at such a state of nervous 

 tension during the period of sexual activity, that the 

 female will curl her abdomen at the slightest touch and the 

 male will at first grasp any rounded object presented to 

 him and attempt to overturn it. A stimulus so slight as 

 the slow lowering of the water when I siphoned it from 

 the closed tank, was sufficient to cause violent activity 

 among the males, with the result that all the females were 

 soon held by males. 



Pearse, in a study of crayfish made in the laboratory 

 with no attempt to reproduce natural conditions (40), has 

 made many interesting observations and experiments, 

 verifying my statements (21) and adding the discovery 

 that a male will copulate with a dead female. He dis- 

 covered that the male of one species had succeeded in ad- 

 justing his stylets to the annulus of a dead female of 

 another species. 



Andrews has just published a paper (13) in which he 

 mentions seeing males attempt to copulate with dead and 

 bound or paralyzed males and to actually go through all 

 the activities of mating with dead females except the in- 

 jection of the spermatophores and plugging of the annu- 

 lus. He agrees with my previous statement that the males 



