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CLASSIFICATION. 



Classification of the Ophiuroidea. 



The Ophiuroidea are all provided with five arms ; in the greatest number they are 

 simple, but in a few they are branched ; this character enables us to form a binary 

 division of the order into two famihes, the Ophiurid^e and the Asterophydi^. From 

 the number and position of the genital fissures in the interbrachial spaces, we obtain a 

 character for the division of the families into tribes. The structure of the disk, the 

 presence or absence of scales, plates, or other clothing on the same, the structure and 

 development of the rays and the spines which arm its lateral plates, the structure of the 

 mouth and oral fissures with their armature, the development of the maxillae and their 

 dcntary plates, afford collectively good generic characters. 



OPHIUROIDEA. 



Characters. 

 A. Two or four genital fissures. 

 a. Arms, five, always simple. 



Families. 



OpHIURIDiE. 



B. Ten genital fissures. 



b. Arras, five, simple or ramified. 



ASTEROPHYDI^. 



1st. Family OpHiuRiDit:. 



Four genital fissures in each interbraciiial space. 



Genera. 

 Ophioderma. 

 Ophiocnemis, 



Two genital fissures in each interbrachial space. 

 A. Disk covered with hard plates. 



Ophiolepis. 



Ophiopeza. 



Ophionereis. 



Ophiura. 



Ophiocten. 



Amphiura. 



Ophiactis. 



Ophiostigma. 



Pectinxcra. 



Ophiocoma. 



Ophiaraehna. 



Ophiacanctha. 



Ophiomastix. 



Acroura. 



Aspidura. 



Aplocoma. 



