THE STELLEROIDEA 



277 



ORDER 4. Zygophiurae, Bell (1892). 



Ophiuroidea in which the movement of the ossicles on one another is 

 limited by the development of lateral processes and pits. Superior, 



Fio. XXXII. 



Astrophyton Llncki. Abactinal surface. (From Wyv. Thomson.) 



The 



inferior, and lateral spine-bearing arm-plates are always present 

 arms are simple and cannot coil round straight rods. 



FAMILY 1. OPHIODERMATIDAE. Zygophiurae with oral papillae 

 numerous, and none infra-dental. Arm incisures on the disc. Dental 

 papillae absent. Genera Ophioderma, Mull. & Trosch. ; Ophiopeza, Peters ; 

 Ophiarachna, Mull. & Trosch.; Ophiocoeta, Liitk.; Ophioconis, Liitk.; Ophio- 

 plax, Lym. ; Ophivyona, Stud. ; (?) Ophiopyrgus, Lym. ; Ophiopyren, Lym. 



