122 NUDIBRANCHIATA.—EOLIDIDA. 
diately seized by the papille of the tongue, which, 
being sharp and directed backwards, continually 
drag by a kind of peristaltic movement the alimen- 
tary materials into the cesophagus.”’* 
FAMILY EOLIDIDZ. 
The animals of this family have a_ peculiar 
elegance, delicacy, and beauty. ‘They have the 
branchiz arranged along the sides of the back. In 
one genus, which links this family with the pre- 
ceding, these organs are branched, resembling little 
leafless trees; but in general they are warts of a 
long oval or spindle shape, pointed at the extremity. 
Their surface is covered with strong cilia, which con- 
stantly maintain a vigorous vibration, by the action 
of which currents of the surrounding water are 
continually poured along each of the papilla, as 
these organs are named, affording the necessary 
oxygen for renewing the vital power of the blood. 
There is reason to believe, however, that the whole 
surface of the body, which is also covered with 
cilia, assists in respiration. 
The papillee are permeated by a canal, which in 
many of the species is brilliantly coloured, con- 
tributing largely to the exquisite beauty of these 
little animals, This canal is connected with the 
stomach and the digestive function, supplying the 
place of the liver in other animals. In the prin- 
cipal genus of the family, each papilla is furnished 
with a curious organ; it is a little oval bag placed 
at the extremity of the papilla, and opening by a 
very minute aperture at its tip. Within the bag 
* Jones’ Anim. Kingd. 410. 
