156 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the first abdominal segment, which is not very wide at any time, can 
no longer be detected in sections. The otocysts are functional and 
orientation is definite. Internally the livers, lateral caeca, green 
glands, and sexual glands are thoracic. The unpaired intestinal 
caecum is lacking and the muscles and blood vessels are similar to 
those of Macrurous Decapoda. 
In color, the glaucothoe resemble zoeae except that the branches 
of the yellow chromatophores form a fine network over the limbs 
and carapace and produce a grayish effect. As before, the stomach 
and intestine are usually empty and transparent and the livers con¬ 
tain refractive globules. 
Glaucothoe are found at the surface, either swimming or clinging 
to floating seaweed and seem to be more abundant at night. When 
swimming, the dorsal surface is uppermost, the abdomen is extended 
while the limbs are either extended or hang stiffly down. Though 
phototaxis is still present, at times individuals cease swimming and 
crawl about on the bottom of the aquarium. These examine the 
objects in their path, and if they find a shell or other hollow object, 
may enter it and abandon the free-swimming life. Quite frequently, 
however, after a brief exploration the larva will recommence swim¬ 
ming. More rarely, a glaucothoe that has already entered a house 
will abandon it. As the sixth stage approaches, the desire for a 
covering for the body becomes stronger with the alterations in struc¬ 
ture until it is almost impossible to keep the larvae “naked.” They 
use all available objects or ensconse themselves in crevices. A house 
may be taken at any time during the phase, but a short period of 
free-swimming life is typical. 
Not infrequently a glaucothoe will remove bits of rubbish from a 
shell, but I was not able to confirm Agassiz’s observations (’75) 
where his young tore out and ate dead snails and then used the 
shells. Glaucothoe, according to my observations, take but little 
food. If, however, his reference is to adolescent crabs, they are 
quite voracious and might readily eat a dead snail, though I have 
observed nothing of the sort. It is, however, scarcely necessary to 
assume or suggest a causal sequence between this act and the use 
of the shell for a dwelling. 
The glaucothoe stage as a rule lasts only four or five days, but 
during this time a profound modification of structure takes place. 
The livers, sexual glands, and green glands pass into the abdomen, 
