PEDICELLATA. 391 
and which terminate near the mouth. They form a system distinct 
from that of the intestinal vessels observed in some species *. 
Linnzus divided them into three very natural, but numerous 
genera, and composed of such various species, that they may be con- 
sidered as forming three families. The 
AsteriAs, Lin., 
Or Starfish, have been so called because their body is divided into 
rays (generally five), in the centre of which, and underneath, is the 
mouth, that is also the anus. 
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 con- 
vey it into the general cavity for a sort of respiration. On the mid- 
dle of the body, and a little on one side, is a stony plate, with a cor- 
responding internal canal, filled with a calcareous matter, which is 
thought to serve for the growth of the solid parts. Internally we 
find a large stomach, immediately on the mouth, from which two 
cca proceed to each ray, ramifying like trees, and suspended (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 vertebree 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 
* For details respecting the organization of the Star-fish, Ursini and Holo- 
thuriz, see the splendid anatomical Monograph of Tiedemann, Landshut, 1516, 
in folia. 
