MONOGRArH OF JAPANESE OPHIUEOIDEA. 



303 



This species is distinguished from 0. imhricatus chiefly by tlie 

 longer genital slits and by the more numerous 

 supplementary dorsal arm plates. Further, the 

 disk scales and the supplementary plates are 

 coarser, thicker and more convex in 0. imhri- 

 catus than in 0. japoniciis. I suppose that, 

 Maektanner-Tukneeetschee's specimens from 

 Enoshima are to be referred to the present 

 species, because the occurrence of 0. imhricatus 

 there is very improbable. 0. japonlcus is 

 undoubtedly the most common ophiuran around 

 Misaki, and perhaps along the entire southern 

 coast of Honshu. It occurs together with 

 Ophiarachnella gorgonia, but is far more abund- 

 ant. In a large specimen in my hands, there are four arm spines 

 in some of the proximal free arm joints. 



Fig. 84. Ophioplocus 

 japonicus. x 5. a. 

 Side view of three 

 .arm joints ne.ar disk. 

 h. Dorsal view of 

 four arm joints near 

 disk. 



Family 2. Ophioleucidse Matsumoto, 1915. 



Disk flat, covered with very thick scales with superficial 

 granulations. Radial shields naked or covered with granules ; in 

 internal view, they are very large and joined or very close -set in 

 pairs. The radial shield and genital plate articulate with each 

 other by means of two condyles and one pit. Genital shts very 

 long, extending from the oral plate to the disk border, sometimes 

 onto the dorsal side of the disk. Oral and adorai shields of 

 moderate size or often large ; each interradial pair of the latter 

 joined to each other just inside the former. Numerous close -set 

 oral papillae, arranged in a single row. Dental papillae absent. 

 Teeth arranged in a single vertical series. Peristoraial plates 



