OPHIUROIDEA 



57 



caeca are absent, and the anal opening is lacking. The madre- 

 poric plate is on the oral side. 



Food. They are carnivorous, feeding upon worms, crabs, and 

 shell-fish. They are also scavengers. 



Multiplication. Some lay their eggs in the water, where they 

 are fertilized and develop into a pluteus stage like that of the 



Fig. 43. Gorgonoceph'alus agassiz'ii (one-fourth natural size). Oral view. 

 (Clark, in Bulletin 550, U. S. F. C., 1902.) 



Echinoidea, while others are viviparous and care for their 

 broods. In many species there is also a kind of asexual repro- 

 duction, the animal dividing through the disk and each half 

 regenerating its " other half." 



There are several hundred species known. These echino- 

 derms are variously called brittle-stars, serpent-stars, and sand- 



