1^1 ZOOLOGY. 



a sort of stalk. Such are, or rather were, the encrinida* 

 (Fig. 4(57). now rarely met with, but which once existed in 

 great numbers in the seas of various geological epochs. The 

 holothuria are remarkable for the disposition of their ropira- 

 tory apparatus, composed of membranous tubes ramified like 

 a tree, and receiving water into the interior through the 

 intermedium of a cloaca or anus. 



CLASS OF THE ACALEPH.E. 



618. The acalephae are soft animals, of a gelatinous 

 consistence, always floating in the sea, and formed essentially 



Fig. 469. Meduse Pelagie (Sea Blubber, Medusa Pelagia). 



tor swimming. Their organization is very simple : the >kin 

 is not distinct from the subjacent parts, and their internal 

 organs are reduced to a cavity or stomach, communicating 

 with the exterior by a single opening, and giving rise to 

 canals extending into the different parts of the hody. and 



