92 PROCEEDINGS OF THE ACADEMY OF [Feb., 



AA — Radial shields long and very narrow, bar-like, each pair approxi- 

 mating each other at the outer ends; numerous arm spines; 

 two tentacle scales, of which the abradial one is minute and 

 acute, and the adradial one is very long and lanceolate, 



Ophiopsilin^. 



Subfamily 1. OPHIOCOMIN^ nov. 



(Characters as given above in key.) 



This subfamily includes Ophiopteris, Ophiocoma, Ophiomastix and 

 Ophiar thrum. 



Subfamily 2. OPHIOPSILIN.E nov. 



(Characters as given above in key.) 



This subfamily is formed by a single genus, Ophiopsila. 



Though Ophiopsila is referred to the Amphiuridse by certain 

 authors, it fundamentally differs from the latter in the internal 

 structures. The oral frames have well-developed lateral wings, as 

 in the Amphiuridse, Ophiotrichidse, Ophioceramis, Ophionereidinse 

 and Ophiocominse. The oral and dental plates are 7t -shaped (instead 

 of being x-shaped) in common outline in internal view, quite as in 

 Ophioceramis, the Ophionereidinse and Ophiocominse. The genital 

 plates are entirely free from the basal vertebrae and have two condyles 

 and one pit at the outer end to match two condyles and one pit of 

 the radial shield, as an important characteristic of the Chilophiurida; 

 while those of the Amphiuridse and Ophiotrichidse are firmly fixed 

 to the basal vertebrse and have only a single large condyle to match 

 one large socket of the radial shield. The genital scales are long, 

 narrow and bar-like, also a characteristic of the Chilophiurida; 

 while those of the Gnathophiurida are short, very flat and leaf-like. 

 As to the external characters, the presence of both oral and well- 

 developed dental papillae hinders any reference of Ophiopsila to 

 either the Amphiuridse or Ophiotrichidae. In short, Ophiopsila is 

 referal)le only to the Ophiocomidae, being, however, distinguished 

 from the other genera of that family by certain characters of second- 

 ary importance. 



