VARIETIES OF STAR-FISHES. 223 



sure. When this pressure is withdrawn, the 

 liquid retreats into the gland, and the feet col- 

 lapse. Thus by this simple and effective mecha- 

 nical arrangement the star-fish can either retract 

 or extend his feet at will. Individually the 

 suckers exert little power, but their collective 

 force is fully adequate to all the animal's require- 

 ments. 



The Ophiuridce (ophis, a serpent, and oura, a 

 tail) are very common along our sea coasts. This 

 generic term by which they are known, a name 

 assigned them by the celebrated naturalist, Pro- 

 fessor Edward Forbes, accurately describes their 

 general form. Their bodies, small and round, are 

 furnished with fine, long, and slender arms. These 

 arms, instead of the sluggish movement of the ordi- 

 nary star-fish, are endowed with great activity, and 

 move and twist about with great rapidity, and, by 

 their resemblance to the tails of small serpents, 

 suggest the name by which they are distinguished. 

 The celerity of motion possessed by these arms 

 furnishes the creature with power to crawl with 

 considerable rapidity. 



Another beautiful variety is the Comatula or 

 feather star. It possesses much elegance of form 

 and beauty of colour. Its body is of small size, 

 covered with jointed filaments. Fine, long, and 

 slender arms, feathered along their sides and fur- 

 nished with claws, enable it to adhere to rocks or 

 seaweed with great force. Its internal structure 

 is most elaborate and wonderful, and cannot be 

 well described without recourse to very minute de- 



