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MANUAL OP ZOOLOGY. 



In Euryale the body is in the form of a sub-globose disc with 

 five obtuse angles, and the arms are prehensile. In Astero- 

 phyton, the Medusa-head star, the arms are divided from the 

 base, first dichotomously, and then into many branches. In 



Fig. 35. Ophiuroidea. Ophiocoma neglecta. 



Ophiura, the sand-star, the arms serve for reptation (creeping), 

 and are undivided, often exceeding the diameter of the disc 

 many times in length. 



The order Ophiuroidea may be divided into two families, as 

 follows : 



Family 1. Ophiuridca. 



Genital fissures two or four in number. Arms five, always simple. 

 Family 2. Aster ophy dice. 



Genital fissures ten in number. Arms five, simple or branched. 



