MONOGRAPH OF JAPANESE OPHIUEOIDEA. 341 



Oral frames very stout, with extremely well developed lateral 

 wings. The radial shield and genital plate of the same side of a 

 radius articulate with each other ])y means of two articular condyles 

 aud one pit. Arms moderately long, stout, widest at some distance 

 outside the base. Arm plates all well developed. Arm spines long, 

 stout, perpendicular to the arm axis ; the uppermost spines of every 

 second or tliird lateral arm plates often very large and clavate. 

 One or two tentacle scales to each pore. 



This family includes five genera, four of which form a sub- 

 family, while the fi.fth forms another. 



Subfamily 1. Ophiocomince Matsumoto, 1915 : — Eadial shields 

 very stout, boot- shaped, those of a pair widely separated from each 

 other ; three to five arm spines, the uppermost spines of every 

 second or third lateral arm plates being usually very large and 

 club-shaped ; tentacle scales short and leaf-like. 



Ophiopteris Smith, 1877. 



Ophiocoma Agassiz, 1835. 



Ophiomastix Müller & Troschel, 1842. 



Ophiarthrum Peters, 1851. 

 Subfamily 2. OphiopslUnœ Matsumoto, 1915: — Eadial shields 

 slender, bar-like, each pair being rather close together at the 

 outer ends corresponding to the dorsal approximation of the outer 

 ends of the genital plates ; numerous arm spines, none of which 

 is club-shaped ; two tentacle scales, of which the adradial one is 

 very long and lanceolate, while the abradial one is very short 

 and acute. 



Ophiopsila Forbes, 1842. 

 The present family is very uniform in its internal structures. 

 I have dissected all the Japanese representatives of this family, 

 viz., Ophiocoma hrevipes Peters, 0. scolopcndrina (Lamarck), Ophio- 



