258 
E. A. ANDREWS 
with like failure to bring the stylets to the annulus. The vain 
efforts continued more than an hour. 
A male with only the left hook removed succeeded in attaching 
the right hook to the joint of the female's leg but, when the strong 
contraction followed, the hook came out, not being held by its 
opponent force on the opposite side of the body (see fig. 2), and 
then the male was thrown off as before. In this male with one 
hook the animal was seen to change from the right to the left 
and back again to the right leg after vainly trying to make entrance. 
This is taken to indicate that the normal male is in the habit of 
changing legs, as is seen, for the purpose of obtaining perfect 
entrance of the stylet, whether there is a right or a left annulus 
presented, and to indicate that but one of the stylets is used at 
a time. 
After the male with one hook had made several quick thrusts 
of the stylet and encountered no resistance he always settled down 
close to the female and made exploratory palpations with the 
maxillipeds over the bases of the female legs. In one case after 
this examination of the bases of the second and third legs, a few 
rods of sperm were seen upon the telson of the female, showing 
that abnormal, premature discharge of sperm had taken place 
though the stylets had not been introduced. 
In these males without hooks failure to gain entrance of the 
stylets was followed by advance of the body and palpation of 
the b^ses of the legs of the female before the next attempt. This 
raises the question whether in normal conjugation the male may 
have a complex knowledge of the form of the female, or may 
judge by sensing the surface of the female whether a change of 
position will lead to better results. At all events after failure there 
is the use of sense organs and then renewed trial. 
Bearing upon the conjugation of this one species are the recorded 
facts as to conjugation in other species and the following facts 
as to attempts of one species to conjugate with another. 
It will be shown elsewhere that the stylets in probably all 
Cambari are alike in use and essential structure despite remarkable 
differences in general proportions and external appearance. 
