ORDER PEDICELLATA. 439 
cavity, in which distinct viscera are floating. A sort of vascu- 
lar system, which, in truth, does not extend to the whole 
body, keeps up a communication with divers parts of the 
intestine, and with the organs of respiration, which, most 
generally, are also very distinct. We even observe in several 
species, some filaments which might perform the nervous 
functions, but which are never distributed with the regularity, 
and in the fixed order, which exists in the other two divisions 
of invertebrata. 
We divide the echinodermata into two orders: those which 
have feet, or at least vesicular organs, to which this name has 
been given, and those which are destitute of them. 
FIRST ORDER OF ECHINODERMATA. 
THE PEDICELLATA 
ARE distinguished by organs of motions altogether peculiar. 
Their envelope is pierced by a great number of small holes, 
placed in very regular series, through which pass some cylin- 
drical, membranaceous tentacula, terminated each by a small 
disk, which performs the office of a cupper. ‘The part of 
these tentacula which remains in the interior of the body is 
vesicular. A fluid is spread through all their cavity, and is 
carried, at the will of the animal, into the external cylindrical 
part, which it extends, or it re-enters into the internal vesi- 
cular part, and then the external part sinks in. It is by 
elongating and contracting in this manner, their hundreds of 
little feet, or tentacula, and fixing them by the cuppers, which 
