242 E. A. ANDREWS 
leg; (7) Hooking; (8) Advance; (9) Recession; (10) Palpation; 
(11) Contraction of abdomen and claws; (12) Entrance; (13) 
Thrusts of stylets; (14) Discharge of sperm; (15) Formation of 
plug; (16) Withdrawal; (17) Liberation of female. Some of 
these phases are very brief, some less essential, and pauses of longer 
or shorter duration come into the series of active states. 
The part of the female during all these phases of conjugation, 
which may consume as many as nine hours, is chiefly a passive 
one, at least after the initial stages. 
When the female is seized she generally struggles as if to escape 
and also defends herself with her claws more or less vigorously. 
The actual seizure by the male may well supply a strong stimulus 
to the female, since the male's chelae frequently close firmly upon 
the limbs of the female on one side while at the same time holding 
the rostrum, eyes and bases of the antennae. At this stage the 
female frequently makes violent leaping movements, backward, 
which however, may only facilitate the turning of the female over, 
since the female in these leaps becomes suspended in the water, 
while the male remains supported upon his legs and has the better 
leverage. 
Once the female is turned over by the male she remains through 
the following states so passive that she appears dead and the 
above male that tried to conjugate with a dead female probably 
missed little reaction from the female. This passive state seems 
to be like the hypnotic condition which Dearborn says results 
from the holding of crayfish in any constrained position. In this 
state there is not a relaxation of all the muscles but a strong flexure 
of the abdomen, which remains coiled. This coiling of the abdo- 
men is lacking in a dead crayfish and it may be of some aid in the 
process of conjugation, since the telson of the male is pushed 
against the coiled abdomen in a way that seems to aid in the lever- 
age that makes possible the thrusting of the stylets, as will be de- 
scribed later. 
A striking difference between the male and the female during 
conjugation is the fact that while the male carries on violent 
vibratory or fanning movements of the exopodites about the mouth 
(which may be in part a sign of excitement), the female remains 
