ECHINODERMATA, . 113 
manner, so as to form a more or less feathery crown. In one of 
our living forms, the animal, when full grown, is free; but in all 
other living species, and in the great majority of fossil forms, 
the. body was attached 
throughout life to the sea- 
bottom by means of a 
jointed stalk attached to 
the lower surface of the 
cup (fig. 47). 
The commonest living 
species is the rosy feather- 
star (Comatula rosacea), 
which occurs not very 
rarely on certain parts of 
our coasts (fig. 46). This 
beautiful animal consists | 
of a central body or disc, 
from which proceed five 
radiating arms, which di- 
vide almost directly after 
‘their origin into two second- 
-ary branches, so that ulti- 
mately there are produced 
ten long and slender rays. 
Each arm is furnished on 
both sides with a number 
of little jointed lateral pro- 
cesses or “ pinnz,” so as to 
assume a feather-like ap- 
pearance, from which its 
popular name is derived. 
The digestive system is 
furnished with both a 
mouth and a vent; the 
water-vascular or ambu- 
lacral system appears to 
take no part in locomotion, 
and the reproductive or- 
gans are lodged in- the 
lateral processes of the arms. 
4 
Fig. 47.—Rhizocrinus lofotensis, a living 
stalked crinoid (after Wyville Thomson), 
four times the natural size. a Stem; & 
Cup ; cc Arms. 
The most remarkable point, how- 
ever, about the Comatuda, is the manner in which it develops 
H 
