MONCGEAFH OF JAPANESE OPHIUEOIDEA. 257 



infradeiital papilloc at the apex of each jaw, much longer and 

 stouter than the other oral papillae and rather obtusely pointed. 

 Five teeth, very small, close- set, obtusely pointed. 



Arms very short, stout, tapered rapidly outwards. Dorsal arm 

 plates fan-shaped, about as long as wide, convex dorsally. Lateral 

 arm plates convex, those of the two sides separated both above 

 and below in the basal arm joints. First ventral arm plate large, 

 triangular, with obtuse inner angle and convex outer side, wider 

 than long. The following plates are octagonal, with very short 

 inner lateral and outer lateral sides, the former concave at the 

 tentacle pores ; wider than long, wider without than within. From 

 the sixth or seventh outwards, the plates are longer than wide, 

 hexagonal, with very short inner and inner lateral, concave lateral 

 and very convex outer sides. Seven or eight arm spines, including 

 the tentacle scales, in the free basal joints, fine, conical, short ; 

 middle ones longer than the upper and lower ones, and about 

 half as long as the corresponding arm joint ; diminishing in number 

 outwards. The lower spines are much finer and serve as tentacle 

 scales. The second oral tentacle pore is very large, opening outside 

 the oral slit, bounded by three or four scales on both the abradial 

 and adradial sides. The tentacle pores are also large, and bounded 

 in the basal joints by one to three aboral scales, besides the lower 

 arm spines on the adorai side. 



Colour pale gray in alcohol. 



The arm length varies from one and a half to two 

 and a half times of the disk diameter. The disk plates, in- 

 cluding the primaries, are often very irregular in size and 

 arrangement. One monstrous specimen has six arms, of which 

 two arise from a common base, corresponding to a pair of radial 

 shields. 



