THOMPSON: METAMORPHOSES OF HERMIT CRAB. 157 
the circulatory system is modified, and the muscles and pleopods 
degenerate, so that before the moult to the sixth stage closes the 
period, the anatomy has become adult in plan. This metamorphosis 
is not dependent on the presence of a body covering, but completes 
itself perfectly in larvae which are prevented from obtaining a shell. 
The whole animal also becomes less transparent, the chelipeds 
become white, and brown bands appear on the posterior pereiopods, 
a coloration recalling that found in the adult Eupagurus annulipes. 
The moult to the sixth stage is preceded by a brief period of 
quiescence, and in the few cases observed, the actual ecdysis was 
rapid. Either the integument of the thorax is sloughed first and 
that of the abdomen later, or the entire integument is sloughed in 
one piece. The latter method seems to be the rule for the zoeal 
ecdyses, while the former is more frequently the rule in the adult, 
and the abdominal exuvium is usually badly torn in the process. 
The glaucothoe stage is the “noch altern Jungern ” of Rathke 
(’40, ’42); the “Glaucothoestufe ” of Muller (’64) ; the “third stage ” 
of Bate (’68) ; “stage when it seeks a shell” of Agassiz (’75), anrl 
the “first postlarval,” “first adolescent” of Sars (’89). It is not 
mentioned by other workers with the exception of Czerniavsky (’84). • 
Adolescent phase .— “ Adolescent phase ” is more a convenient 
term under which to discuss the development during the earlier 
postlarval life, before the adult anatomy is fully attained, than a 
definitely limited period. There is also little to be gained by an 
attempt to separate the numerous stages which may be included 
within it. The crab has the adult structural plan before the close 
of the glaucothoe period, but all the organs must still undergo devel¬ 
opment to realize fully the adult structure. The length of this 
process varies widely in different parts. 
Sixth-stage larvae are of the same size as glaucothoe, and the 
specific adult form may be attained before much growth occurs. 
After about forty days have passed, the young reach a length of 
from five to eight millimeters. The sixth stage lasts from six to 
twelve days, but the later moults are irregular and crabs of the 
same age may be very unlike in size and development. The 
manner of life in all the adolescent stages is that of the adult, and 
food is taken abundantly almost immediately after the moult from 
the glaucothoe. 
The sixth stage retains the anmdipes color, handed to it by the 
