ORDER PEDICELLATA. 445 
of three, the second of five, the third of ten, all three with 
crests; then follow some with more numerous lamine. 
Finally, the central body may be all of one piece, but 
which appears to be composed of five cemented together. 
These are the EUGENIACRINITES. 
The fossil productions, known under the name of Entrochi, 
are pieces of the stem and of the branches of animals of this 
genus. 
EcHINUS, Lin. Vulgo Sea urchins. 
Have the body clothed with a testa, or calcareous crust, com- 
posed of angular pieces, which join exactly, and are pierced 
with several very regular ranges of innumerable small holes, 
through which pass the membranous feet. The surface of 
this crust is armed with spines articulated on little tubercles, 
and moveable at the will of the animal, to whose motions they 
administer, conjointly with the feet, which are situated be- 
tween them. Other membranous tubes, much finer, and 
often divided at their extremity, probably serve to introduce 
and to expel the water which fills the interior of their shell. 
The mouth is furnished with five teeth, enchased in a very 
complicated calcareous frame- work, resembling a lantern with 
five panes, furnished with divers muscles, and suspended in a 
large aperture of the testa. These teeth, in the form of long 
bands, grow hard towards their root, in proportion as they 
are worn at the point. The intestine is very long, aud at- 
tached spirally to the interior parietes of the testa by a mesen- 
tery. A double vascular system runs along this canal, and 
extends partly over the mesentery, and there are also particu- 
lar vessels for the feet. Five ovaries situated around the anus 
empty themselves each by a particular orifice. They form 
the eatable part of these animals. 
The echini subsist more especially on small testacea, which 
they seize with their feet. Their motions are very slow. 
