bo 
Or 
i=) 
COMPARATIVE ZOOLOGY. 
Cuass I1.—Asteroidea. 
Ordinary Star-fishes consist of a flat central disk, with 
five or more arms, or lobes, radiating from it, and con- 
taining branches of the viscera. The skeleton is leathery, 
hardened by small calcareous plates (11,000 by calcula- 
tion), but somewhat flexible. The mouth is below; and 
the rays are furrowed underneath, and pierced with nu- 
merous holes, through which pass the sucker-like tenta- 
cles—the organs of locomotion and prehension. The red 
spots at the ends of the rays are supposed to be eyes. The 
usual color of Star-fishes is yellow, orange, or red. They 
Fic. 207. — Under - surface of Star-fish (Goniaster reticulatus), showing ambulacral 
grooves and protruded suckers, 
