No. 2.] PLANOCERA INQUILINA. 201 
of August. The egg-string is spiral (Fig. 2), varying in breadth 
at different points and fixed quite firmly to the glass. It con- 
sists of a perfectly transparent gelatinous substance in which 
the small white eggs are embedded in a single layer. Each egg 
is inclosed in a delicate capsule probably secreted by the shell- 
gland surrounding the egg-duct. The helicoid shape of the 
string is evidently due to the animal’s moving about in a spiral 
path during oviposition. Frequently the strings present more 
turns and more irregularities than the one figured. 
I failed to follow the development of the eggs beyond the 
extrusion of the polar bodies and the first cleavage stages, as 
my material died. The water, though constantly renewed, was 
probably too warm, the mollusks, in which the eggs would 
normally have been laid, being found 6 or 8 fathoms below the 
surface. The animals themselves did not long survive in the 
aquarium. <A slow process of dissolution set in at some point 
on the body, and gradually more and more of the tissue melted 
away till only the tentacle- and brain-region remained. This 
crept about for a few days, but finally it, too, disintegrated. 
THE UNIVERSITY OF CHICAGO, 
May 12, 1893. 
