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E. A. ANDREWS 
reactions and instincts used both in the processes of conjugation 
as well as in laying and caring for the eggs. 
The male, while lacking the female organs and instincts, has 
testis and deferent ducts as well as three pairs of external organs 
directly concerned in the transfer of the sperm to the receptacle 
of the female. The male shows characteristic proportions of 
various parts of the body and has a pair of special clasping-hooks. 
The male also possesses a series of complex abilities that are 
shown in the processes of conjugation. 
The phenomena of conjugation are, in brief outline, the follow- 
ing: The aggressive male seizes the comparatively inert female 
and mounting upon her ventral surface becomes firmly attached 
both by the large chelae and by special clasping-hooks on the 
bases of the legs. The sperm that issues from the deferent ducts 
through soft protrusions which we shall call the papillae, is con- 
ducted by the combined action of the first and second limbs of 
the abdomen into the special receptacle in the shell of the female, 
The male has three sets of organs concerned in the transfer of 
sperm, the papillae and the two pairs of specialized limbis. These 
limbs we shall call the stylets, as they are firm, calcified, tapering 
organs that are thrust with force into the narrow slit of the cal- 
cified receptacle in the shell of the female. By means of these 
stylets the sperm is transferred some half-inch or so through the 
water from one animal to the other without being exposed to 
contact with the water, which would, it is believed, destroy the 
sperm. 
During most all the time of conjugation the male is tirmly 
locked to the female in the attitude shown in fig. 1, which is 
from a photograph of living crayfish under water. ^ The female is 
supine and relaxed except for the tightly rolled abdomen that is 
embraced by the tensely flexed abdomen of the male. The male 
is poised over the female and balanced right and left by the tip 
of but few legs, while the other legs hold the female, the great 
^ An excellent photograph of a different phase of conjugation in this same species 
was made from live crayfish under water by R. W. Shufelt and published by him 
in "Shooting and Fishing," 1898, and in "Natur und Haus," 1903, and by J. 
Arthur Harris in Sc. Bull. Univ. Kansas, 1903. 
