t>26 



KADI ATA. 



THE SHETLAND A RODS. 



ORDER 3. STELLERIBA. 



This order is composed of animals with a flattened and more or less pentagonal body, several 

 families hearing 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 Fedicellanoe. 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; 

 along the lower surfoce of each arm runs 

 a very distinct furrow, from w'hicli the am- 

 bulacra are protruded. 



THE EURYALID^. 



The Stcllerida are usually divided into 

 three families. The first, the Euryalida, 

 have the arms distinctly separated from 

 the body, always much branched, and 

 usually furnished with cirri, producing the 

 confused and tangled appearance which has caused them to be compared to and named after the 



THE COMMON BRITTLE-STAR. 



