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E. A. ANDREWS 
a half hour later the right leg was crossed anterior to these remain- 
ing right stylets. In this state the right second stylet was seen 
to swing back and forth by its own muscles through 70 degrees, 
quickly, before locking to the first. Two hours later the male had 
separated without leaving any sperm plug, but as this same result 
always followed when the males were thus mutilated the male had 
carried out the process of conjugation on the female of another 
species as far as would have been the case on the same species. 
The possibility of crossing is thus good, and its failure would 
come from some mechanical difficulty rather than from the lack 
of the instinct to conjugate with any passive crayfish. Of course 
the fertilization of the egg may be ruled out by some inability 
of the egg and sperm to combine, but it seemed worth while to 
fill the annulus naturally or artificially with sperm of another 
species and await the result the following year. 
The sternal plates of many females were cut off and fastened 
to females of another species, so that these now had their own 
sperm receptacle replaced by that of another specie^. But though 
some of these mutilated females lived to lay eggs, the eggs did 
not develop and the experiment failed. Attempts to have such 
transplanted receptacles filled by males also failed. 
The male of C. viriUs will also respond to the females of C. 
affinis as is shown by the following : A female C. affinis was put into 
the dish inhabited by a male C. virilis. The male in two hours had 
seized the female and was holding her chelate legs in normal 
manner and was trying to get the left fifth leg in advance of the 
stylets, which was difficult on account of the fact that the great 
length of the stylets of this species made them strike against the 
fifth leg, which was held with the elbow, or joint between the third 
and fourth segment from the tip, pressed against the thorax of 
the female. But finally the male rose up far enough away from 
the female to allow of the stylets being placed anterior to the fifth 
leg. While making these efforts the first and the second stylets 
were fastened and unlocked several times; when the second sty- 
lets were free they were swung back and forth quickly, while 
the first rested forward horizontally under the thorax. Then the 
first were raised a short way by their own muscles, but then be- 
