CONJUGATION IN THE CRAYFISH, CAMBARUS AFFINIS 251 
in the conjugating attitude the males were little excited by them 
till moved about by a pair of forceps, but even then were less 
excited than by the normal moving of the female. One male 
mounted upon such a tied female that happened to lie supine and 
then struggled to carry on conjugation, advancing and receding 
over the female, grasping with the legs and abdomen and violently 
palpating with the third maxillipeds. Finally, when, in the 
pressure of the male's chela along the female's chela, the bands 
came off, the male used the chelae normally. 
In another case, however, the male, though having lost one 
chela, used the single bound one so effectively that a female 
with chelae bound but otherwise free was conjugated with rather 
completely. That is, the female being found upside down was 
mounted and held. She lapsed into the normal inert state, how- 
ever. The male mounted and grasped with legs and abdomen 
and crossed one fifth-leg above the erected stylets, then hooked 
to the female and made tamping movements with the abdomen. 
After that the body was elevated in front and force exerted to 
drive the stylets in. The male shoved the single bound chela 
against the face of the female and thus made a substitute for the 
usual grasp. 
This attempt at complete conjugation without normal use of 
chelae lasted an hour and more and the fifth leg was changed to 
the other side. Eventually the male desisted and though sperm 
had been seen to issue from one of the first stylets there was no 
sperm plug in the annulus. 
Evidently, however, the male with bound chelae neither is 
lacking in keen response to the female nor in instinct to carry on 
as many of the phases of conjugation as possible, though the first 
acts may be represented only by internal phenomena without 
complete external expression. 
Coming to the anatomical side, we find three pairs of organs 
in the male absolutely necessary for the transfer of sperm in these 
complex processes of conjugation, and there are also in this cray- 
fish two spurs or hooks on the legs, the importance of which has 
not been described. We will here describe only these hooks, 
reserving an account of the anatomy of the other organs more 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 9, NO. 2. 
