MOXOailAPIt OF JAPANESE OPHIUIIOIUEA, 825 



are rather small, and often covered with granules on their 

 inner borders. One of the specimens from Okinawa notably 

 departs from the typical ones. It is only 6 mm. across the disk. 

 The radial shields are almost covered with granules. Moreover, 

 in the arm bases, granules which are finer than the disk granules 

 occur on the ventral abradial parts of the lateral arm plates, on 

 the proximal parts of the same under the arm spines, along the 

 dorsal border of the same, and along the distal border of the 

 dorsal arm plates. 



OphiavaehneUa megalaspis Clark. 



Opliiararhiella megalasj^is : Clark, Bull. U. S. Nat. Mus., LXXV, 1911, 

 p. 25, fig. 2. 



Off Suno Saki, Sagami Sea ; 44-50 fatlioms (Claek). Eastern 

 fSea ; 95-106 fathoms (Clark). 



Family 4. Ophiochitonidae ^Iatsumoto, 1915. 



Disk covered with fine, imbricating scales, or rarely with fijio 

 granules ; oral angles always free of granules. Five or six oral 

 papillcT on either side of each jaw ; the outermost one is pointed 

 inwards, projecting above the next papilla, which is tlie largest. 

 Teeth arranged in a single vertical row, either triangular and 

 obtusely pointed, or quadrangular, with very stout, truncated end. 

 Dental papilla) absent. Peristomial plates double or triple. Oral 

 frames with or without well developed lateral wings. Radial 

 shield and genital plate of the same side of a radius articulating with 

 each other by means of two articular condyles and one articular 

 pit. Arms long and slender, widest at some distance from the 

 base, horizontally flexible. Dorsal, lateral and ventral arm plates 



