||E*chi`no*der"ma*ta
(&esl;*kī`n&osl;*d&etilde;r"m&adot;*t&adot;), n.
pl. [NL., fr. Gr. 'echi^nos hedgehog, sea urchin
+ de`rma, -atos, skin.] (Zoöl.)
One of the grand divisions of the animal kingdom. By many
writers it was formerly included in the Radiata. [Written also
Echinoderma.]
&fist; The species usually have an exterior calcareous skeleton,
or shell, made of many pieces, and often covered with spines, to
which the name. They may be star-shaped, cylindrical, disk-shaped, or
more or less spherical. The body consists of several similar parts
(spheromeres) repeated symmetrically around a central axis, at
one end of which the mouth is situated. They generally have suckers
for locomotion. The group includes the following classes: Crinoidea,
Asterioidea, Ophiuroidea, Echinoidea, and Holothurioidea. See these
words in the Vocabulary, and also Ambulacrum.
