134 Wisconsin Academy of Sciences, Arts , and Letters. 
which in a natural position lies parallel to and almost touching 
the last upright strand of the chitinous framlework which sup¬ 
ports the legs. The posterior part, which is not more than half 
the length of the anterior, has all the other pieces articulated 
to it. 
What I have taken to he the oopulatory tube, fig. 10 F, arises 
from the basal piece just back of the clasping apparatus. It 
is abruptly curved and ends in a sharp-pointed piece. Being 
unable to follow the vas deferens I could not establish any con¬ 
nection between it and this tube and am not sure whether it or 
the shorter tube, fig. 10G, is the true oopulatory one. The 
clasping apparatus consists of a single piece which is joined to 
the basal part just below the copulatory tube and is normally 
pointed in the same direction. The position and shape of this 
piece is. shown plainly in the figure. To these parts. I would 
add a connecting piece which passes from the upper part of the 
basal piece to connect with the loop of the framework already 
described. 
I was able to observe several pairs in copula but did not see 
the animals unite or determine the length of time they remained 
together. The shell of the male is open clasping that of the fe¬ 
male at least one-third of which is concealed. The mouth parts 
of the male lie along the dorsal edge of the female’s shell; its 
legs are inactive, somewhat drawn up, and lie on either side. 
The second antennae of the male clasp the shell of the female, 
the large claws being inserted between the valvesi, reaching 
nearly to the eye. The first antennae remain free and most of 
the time beat slowly up and down. Naturally the clasping or¬ 
gans and copulatory tube point backward but they are now re¬ 
versed and together with most of the basal past entirely within 
the shell of the female, entering a little above the middle of 
the posterior margin. During copulation the female crawls 
around carrying the male on her back. 
The eggs are laid singly, attached to the basal part of the 
gills or to the long hairs near their base; sometimes, however, 
they are arranged in groups of front six to eight. The young 
when they leave the egg have the two pairs of antennae and the 
mandibles fully developed. Well back on the body are a pair 
