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CLASS I. 
ECHINODERMATA(1). 
The Echinodermata are the most complicated animals of 
this division. Invested with a well organized skin, frequently 
supported by a sort of skeleton, and armed with points, or 
movable and articulated spines, they have an internal cavity 
in which distinct and floating viscera may be perceived. A 
sort of vascular system, which it is true does not extend 
throughout the body, keeps up a communication with various 
parts of the intestine, and with the organs of respiration, 
which are generally very distinct. Threads are also seen in 
several, which may act as nerves, but which are never arranged 
with the regularity and fixed order of those in the animals of 
the two preceding divisions of the Invertebrata. 
We divide the Echinodermata into two orders: those fur- 
nished with feet or at least with vesicular organs, so called 
on account of their fulfilling similar functions; and those in 
which they are wanting. 
(1) The Radaires Echinodermes of M. de Lamarck. 
Vor. [V.—2 R 
