MONOGEAPH OF JAPANESE OPHIUR(^IDEA. 139 



Dorsal arm plates entire, without supplementary plates ; five to 

 eight arm spines, moderately long, conical ; no tentacle scales 

 proper, but tlie lowest arm spine may serve as one. 



Ophiochondrus Lyman, 1869.^^ 



Ophiomœris Kœhl.^11, 190'i { = OpJdurasesCi.MiK, 1911). 



Ophiof/yplis Kœhlek, 1905. 

 Subfamily 2. Hemieuryalince Matsumoïo, 1915. — Dorsal arm 

 plates often accompanied by supplementary plates or replaced by 

 a mosaic of secondary i)lates ; three arm spines and one tentacle 

 scale, both being very slK^rt and flat. 



Sigsbcia Lyman, 1<S78. 



Ophloholcus Claek, 1915. 



Ophioplus A^EEEiLL, 1899. 



Hemieuryale von Maktens, 1867. 

 According to Lyman, Ophiochondrus convohdiis Lytman, 1869 has a 

 a very heavy armature, which lies under the disk skin. The 

 radial shields are bar-hke, long, thick and solid. The genital 

 plates are massive, a full half of the length being occupied by the 

 club-shaped head, while the comparatively small shaft is rounded 

 and tapering. About half way along the length of the genital 

 plate, there is soldered to it the small, rounded genital scale. The 

 peristomial plates are simple, very thick and strong. Within the 

 disk, the vertebrae are short and discoid ; but beyond the disk 

 margin, they take on a curious elongate shape. Their outer face 

 has a wide massive articular shoulder to support the large umbo 

 of the next vertebra ; the articular peg is very small, and there 

 is no distinct hole for its reception in the next vertebra. The 

 important structures of Ophiomœris .pvojecta Matsumoto, 1915 are 



1) Ophioplus armatus Kœhlek, 1907 (referred to Ophiochondrus by K., 1914) and Ophiochondrus 

 granulatus Kœhlee, 1914, are in my opinion referable to the genuine Ophiolehes. 



