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PEDICELLATA. 335 
second of five, and the others more numerous. The two first are 
marked with radiating ridges; 
The RuopoorinitreEs also have several ranges, the first of three, 
the second of five, and third of ten, all the three with ridges, the 
others are more numerous. 
Finally, the central body may be formed of one piece, which ap- 
pears, however, to consist of five pieces soldered together: here we 
have the EuGEntracriniTES(1). 
The fossil productions, known by the names of Entrochites, 
are portions of the stem and branches of animals belonging to 
this genus. | 
Ecurinus, Lin. 
The Echini, or Sea-Urchins, as they are termed, have the body 
invested by a shell or calcareous crust, composed of angular pieces 
which join each other exactly, and perforated by innumerable holes, 
for the transmission of the membranous feet, disposed in several 
very regular ranges. The surface of this crust is armed with spines, 
articulated on little tubercles, that move at the will of the animal, 
whose motions, conjointly with the feet situated between them, they 
effect. Other membranous tubes, much finer and frequently divided 
at the extremity, probably serve to convey water into the interior of 
their shell, and then to remove it. The mouth is provided with five 
teeth, set in an extremely complex, calcareous framework, resem- 
bling a pentagonal lantern, furnished with various muscles, and sus- 
pended in a large aperture of the shell. These teeth, which resem- 
ble long ribands, become indented inferiorly as fast as they are worn 
away at the point(2). The intestine is very long, and attached, spi- 
rally, to the interior parietes of the shell by a.mesentery. A double 
vascular system extends along this canal, and partly on the mesen- 
tery; there are also particular vessels for the feet. Five ovaries, situ- 
ated round the anus, empty themselves by separate orifices; they 
form the edible portion of these animals. 
(1) No one has so carefully studied these productions, or described them so 
exactly as M. J. Miller, in his Wat. Hist. of the Crinordea. Bristol, 1821, in 4to. 
It is to this work that we are indebted for our article. Excellent figures of the 
same are also given by M. George Cumberland, in his Reliquia conservate. 
Bristol, 1826. 
(2) See my Lecons d’Anat. Comp., IV, and the work of Tiedemann already 
quoted. 
