Geschichte dcs Systems. <)09 



2) Trichasteridae: Cladopliiurae with arms branching a few times 

 near their free ends. 



Genera, recent: Trichaster L. Ag., Astroclon Lym. ; Astrocnida 

 Lym., Fossil: Astrocnida Lym. 



3) Gorgonocephalidae: Cladophiurae with arms branching much 

 and from their base. Euryale Lam., Goryonoccphalus Lym., Astro- 

 pliyton Ag., Ophiocrene Bell. 



Ord. IV. Zygophiurae J. Bell, 1892 



mit den Familien: 



1) Ophiodermatidae: Zygophiurae with oral papillae numerous, 

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

 absent. 



Genera Ophioderma Mull, und Trosch. , Ophiopega Peters, 

 OpMarachnq Miill. u. Trosch., Ophiocoeta Liitk., Ophioconis 

 Lutk., Opldoplax Lym., Ophiogona Stud. (V), Ophiopyrgus Lym., 

 Ophiopyren Lym. 



2) Ophiolepididae: Zygophiurae with oral papillae from three to 

 six, of which the last may be infradental. Arm incisures on the 

 disc. Dental papillae absent. 



Genera - Ophiolepis Mull. u. Trosch., Oplnocten Lutk., Ophiura 

 L. Ag., Ophioylypha Lym., Ophioceramis Lym. (V), Ophiochiton 

 Lym., Ophiopaepale Lym., Ophiozona Lym., OpMoplinfhus Dan., 

 Amphiglypha Pohl., Geocoma d'Orb. 



3) Amphiuridae: Zygophiurae with oral papillae from one to five, 

 of which the last is generally infradental. Anns inserted on 

 ventral side of disc. Dental papillae absent. 



Genera Ampliiura Forbes, Ophiocnida Lym., Ophiomusium 

 Lym., OpJiiopeltis Daniels, u. Kor., Ophioccntrus Ljung., Amplii- 

 lepis Ljung., Ophiolepis Lym., Ophiomastus Lym., Ophio- 

 pliyllum Lym., Ophiotrochus Lym., Hemipholis Lym., Ophiactis 

 Liitk., OpJiiopus Ljuug., Ophiopholis Liitk., Ophiacantha Miill. 

 u. Trosch., Ophiotrema Koehl.. PectinuraHQllGi (non Forbes), 

 Opliioplocus Lym., OpMonereis Liitk., Amphipholis Ljung., 

 OphiopTiragmus Lyrn., Ophiostigma Liitk., Ophioblenna Liitk., 

 Ophiooymbvum Lym., Ophiochytra Lym., Opliiolebes Lym., 

 Ophiomitra Lym., OpMocamax Lym., Ophiofhamnus Lyrn., 

 AcrouraA.g., Aspidura Ag., Hemiglypha Pohl., Polypholis Dune. 



4) Ophiocomidae: Zygophiurae with both oral and dental papillae. 



Genera Ophiocoma L. Ag. , Ophiomastix Miill. u. Trosch., 

 Ophiarthrum Pet., Ophiopsila Forbes, OpMopteris E. A. Smith. 



