626 
RADIATA. 
4 
THE SHETLAXD ARGUS. 
ORDER 3. STELLERIDA. 
This order is composed of animals with a flattened and more or less pentagonal body, several 
families bearing five arms of variable length. The mouth opens in the center of the lower surface 
of the disc, and the anus, when present, is always situated on the back. In the neighborhood of 
the mouth some curious prehensile organs are always to be found, which, from the peculiarity of 
their structure and actions, have been regarded as independent parasitic organisms, and described 
as such under the name of Fed ice liar ice. They stand upon little tubercles, and consist of a long 
calcareous stalk, which bears at its extrem- 
ity a singular forceps of three or four pieces. 
These are continually opening and closing, 
apparently for the capture of floating par- 
ticles of food, and, singularly enough, they 
continue their movements even after the 
death of the animal. The skin is coriace- 
ous, and the calcareous matter is deposited 
in it in separate plates, which allow con- 
siderable flexibility to the whole body ; 
alono; the lower sm-face of each arm runs 
a very distinct furrow, from which the am- 
bulacra are protruded. 
THE EURYALID^. 
The Stellerida are usually divided into 
three famihes. The first, the Euryalidce, 
have the arms distinctly separated from 
the body, always much branched, and 
usually furnished with cirri, producing the 
confased and tangled appearance which has caused tbpm to be compared to and named after the 
THE COMMON BBrTTLE-STAR. 
