394 ECHINODERMATA, 
But one very smatl species—Pentacrinus europeéus, Thoms., 
Monog.—is found in the seas of Europe ; it attaches itself to va- 
rious Lithophyta. 
The seas of hot climates produce larger and more complicated 
ones, such as the Ener. asterias, Blum.; Ists aster, L. 
Fossil Encrinites however are very numerous, and so various, that 
they have been divided into several subgenera, according to the com- 
position of the central body placed on the summit of the stem, and 
from which the large rays proceed. 
This body may be formed of pieces articulated with the stem, and 
bearing the rays by similar articulations. In this case, and if thestem 
be round and inflated abuve, we have the AprocrintrEs, Miller ; 
If it be round, but not inflated, ENcrrinires; 
If pentagonal, Penracrinus. 
Or this body may be formed of angular plates united at the edges, 
and forming several ranges. Of these 
The Piatycrintes have but two ranges one of three plates, the 
other of five; 
The Poreriocrinires have three ranges, each consisting of five 
plates ; 
The Cyaruocrinites also three, and each of five, but the last is 
furnished with intercalated plates which may increase it to ten; 
The Acrinocrinites have several ranges, the first of three, the 
second of five, and the others more numerous. ‘The two first are 
marked with radiating ridges ; 
The RwovocrinirEs also have several ranges, the first of three, 
the second of five, and third of ten, all the three withridges; 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 EvGENiAcRINITEs *, 
The fossil productions, known by the names of Entrochites, are 
portions of the stem and branches of animals belonging to this genus. 
Ecuinus, Lin. 
The Echini, or Sea-Urchins, as they are termed, have the body in- 
vested 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 
* No one has so carefully studied these productions, or described them so exactly 
as M. J. Miller, in his Nat. Hist. of the Crinotidea, 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 Religuiw Conservate, Bristol, 1826. 
