PEDICELLATA. 331 
The framework of their body is composed of small osseous pieces, 
variously combined, the arrangement of which merits examination. 
Their power of reproduction is very great, as they not only repro- 
duce the rays which have been separately removed, but a single one 
with the central ray remaining will reproduce all the others; for 
this reason their figure is frequently irregular. In the 
ASTERIAS, Lam. 
Or Asterias properly so called, each ray has a longitudinal groove 
above, the sides of which are perforated by the little holes before- 
mentioned, for the transmission of the feet. The rest of the inferior 
surface is furnished with small and movable spines. The whole 
surface is also pierced by pores, which allow a passage to tubes 
much smaller than the feet, that probably serve to absorb water, 
and convey it into the general cavity for a sort of respiration. On 
the middle of the body, and a little on one side, is a stony plate, with 
a corresponding internal canal, filled with a calcareous matter, 
which is thought to serve for the growth of the solid parts. Inter- 
nally we find a large stomach, immediately on the mouth, from 
which two czxca proceed to each ray, ramifying like trees, and sus- 
pended (each) to a sort of mesentery. There are also two ovaries 
in each ray, and it appears to us that they possess the faculty of self- 
impregnation. A particular system of vessels is connected with their 
intestines, and another with their feet. 
M. Tiedemann thinks that their nervous system consists in a very 
fine thread which surrounds the mouth, and sends a branch to each 
foot, which runs between those organs exteriorly, and gives off two 
twigs internally. 
The osseous framework of each ray consists of a sort of column 
extending along the inferior surface, and composed of vertebrz arti- 
culated with each other, from which proceed the cartilaginous 
branches that support the exterior envelope. Between the roots of 
these branches are the holes that transmit the feet. Other osseous 
pieces, frequently furnished with movable spines, are observed on 
the lateral edges of the branches in many species. 
Some of this genus have the figure of a pentagon with rectilinear 
sides, rather than that of a star. The radiation is only marked ex- 
ternally by the groove of the feet(1). 
7 
(1) Astertas discoidea, Lam., Encyc. Méthod., Vers, XCVII, XCVIII;—As. tesse- 
lata, var., A, Lam.; Link., XIII, 22; Encyc., XCVI. 
