MONOGRAPH OF JAPANESE OPHIUROIDEA. 215 



often beset witli minute spines or stumpy tubercles. Radial 

 shields very large, with a conspicuous articular socket on the 

 ventral surface near the outer end, fitting to the large, ball-like 

 articular condyle of the genital plate. Genital plates firmly fixed 

 to the basal vertebras. Genital scales short, wide, flat, articulating 

 with the genital plates near the outer end of the latter. Besides, 

 there occur a pair of short, flat scales, just outside each oral 

 shield, supporting the proximal abradial border of the genital 

 slits. Peristomial plates small, entire. Oral frames very stout, 

 with well developed lateral wings for the attachment of voluminous 

 masticatory muscles. In internal view the oral and dental plates 

 are very stout, together forming an X- shape. Teeth very stout, 

 widened, squarish. Dental papillœ well developed, forming a vertical 

 clump at the apex . of each jaw. Oral papilLT absent. Arms 

 inserted ventrally to the disk, horizontally flexible or capable of 

 coiling vertically. Dorsal side of the vertebra) Y-shaped, being con- 

 spicuously notched inwards. Vertebral articulation zygospondyline, 

 the articular peg being always present. Arm spines either moderate- 

 ly long, conical and opaque, or very long, flattened, serrate 

 and hyaline. Tentacle pores large, with one or two scales or none. 

 This family includes fifteen genera, as follows. 



Ophlothrix MüLLEE <k Teoschel, 1842. 

 ^ : ; . : Ophiopteron Ludwig, 1888. 

 ■ ■ Ophiçcampsis Dungan, 1887. •' 



■ Ophiotrichoides Ludwig, 1882. ■ ' 



Ophicmasa 'LY},im,.\%ll. ' ' 



OpJiiophthyreus DödeeleiK;,: 1897.'^ 

 ...:• .. ; . Ophiocnemis Müllee &. Teoschel, 1842. 



1) It is possible that, Ophiophthyreiis may be merely a very young st.ige of Ophwmam or 

 Ophiofrifhoides or an allied genus. . , . 



