470 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The exoskeletal pocket is thus closed up except at the left end and 
its bottom is, as it were, pulled away from beneath its mouth, first 
posteriorly, then anteriorly, and then to the right. The pocket lies 
transversely and largely on one side of the annulus except for its 
posterior end. This lies on the other side of the animal, is bent at 
more than right angles with the main length, and turns toward the 
median line. 
Comparative. 
The five species above studied were taken at random and represent 
both low and high groups in the genus so that it is probable that what 
is common to these five annuli will prove to be common to the annuli 
of all species of Cambarus. We may therefore assume that in the 
genus Cambarus the annulus presents a pocket in the exoskeleton 
formed by the epidermis over a protrusion of connective tissue; 
that this pocket is filled with sperm by the abdominal appendages of 
the male; that the sperm is stored up in the annulus till the eggs are 
laid and that it is then discharged and comes into contact with the eggs. 
In other crayfishes observations upon the mode of transfer of sperm 
from the male to the female have been made only in a few European 
species of the genus Astacus. Thus Soubeiran (’ 65 ) stated that after 
three or four hours of union some ten or fifteen threads of whitish 
matter comparable to vermicelli, and each from 7 to 8 mm. long, 
were found on the ventral surface of the female Astacus. Huxlev 
V 
(’ 80 , pp. 39, 135) spoke of the fecundating material as a thiekish 
fluid that formed a white, chalky-looking mass after extrusion and 
stated that it was deposited by the male between the bases of the 
hindermost pairs of thoracic legs and on the anterior abdominal 
somites of the female. 
But the most detailed account of sperm transfer in Astacus is 
that of Chantran (’ 70 , ’ 72 ) who made very extensive observations 
upon the breeding of these crayfish in France. He found that the 
male seized the female and holding her upon her back first placed 
spermatophores upon the expanded appendages of her sixth abdomi¬ 
nal somite and then upon the region about the openings of the ovi¬ 
duct. After ten to fortv-five days the eggs were laid into a mass of 
mucus secreted from the appendages of the abdomen of the female 
