XIX DIPNEUSTI 513 
change in its surroundings the Fish hibernates, or passes into a 
summer sleep, until the next rainy season brings about conditions 
more favourable to active life. Preparatory to this summer sleep, 
and before the ground becomes too hard, the Fish makes its way 
into the mud to a depth of about 18 inches, and there coils 
itself up in a flask-hke en- 
largement (Fig. 307) at the 
bottom of the burrow, which 
is lined by a capsule of 
hardened mucus secreted by 
the glands of the skin." The 
mouth of the flask is closed 
by the capsular wall or lid, 
which is perforated by a 
small aperture. The margins 
of this aperture are pushed 
inwards, so as to form a 
tubular funnel for insertion 
between the lips of the Fish. 
While encapsuled in its 
cocoon the Fish is surrounded 
by a‘soft slimy mucus, no 
doubt for the purpose of 
keeping the skin moist, and 
its lungs are the sole breath- 
ing organs, the air. passing 
from the open mouth of the 
burrow through the hole in 
the lid directly to the mouth Fia. 307.— Diagram of a torpid Protopterus, im 
é : ; situ. c, Cocoon ; e, earth ; 7, funnel leading 
of the animal. The nutri- to the mouth of the Fish ; 7, lid ; m, mouth ; 
tion of the dormant Fish is ee eats burrow ; ¢, tail. (From 
effected by the absorption of 
the fat stored up about the kidneys and gonads, somewhat after 
a fashion not unknown in the fat-bodies of Insects and the hiber- 
nating glands of Rodents. Even portions of the caudal muscles 
undergo fatty degeneration, and thus, in a way which recalls the 
mode of nutrition of the Salmon during the breeding season, and of 
the Tadpole during its metamorphosis, a further store of nutritive 
material becomes available for the sustenance of the Fish during 
VOL. VII 2 Ty 
