NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 253 



tagonal; succeeding plates pentagonal, quickly becoming tetragonal, 

 with distal side convex; all are longer than wide and more or less 

 fully in contact. Side arm plates small, not meeting either above or 

 below; each plate carries three hollow, flat, smooth, bluntly pointed, 

 subequal arm spines, about as long as a joint. Tentacle pores 

 large, each one guarded by two flat, thin, rounded, subequal scales. 

 Color (dried from alcohol), pale brown or dirty whitish. 



Locality. Albatross station 3749, off Suno Saki, Honshu Island, 

 Japan, 83 to 158 fathoms, black sand, shells, 1 specimen. 



Type. Cat. No. 25724, U.S.N.M., from station 3749. 



It is a great pity that the Fisheries steamer Albatross, in her later, 

 more extensive collecting around Japan, failed to meet with this species 

 again. It resembles an Ophioscolex, but the upper arm plates are so 

 well marked and the two tentacle scales so distinct and regular, it 

 will not be confused with any known species of that genus. 



OPHIOSTYRACIUM, new genus." 



Disk covered with a bare skin, upon which are scattered some small 

 thin, roundish plates, a few of which bear a single sharp-pointed spine 

 each. Radial shields evident, long, diverging, each with a conspicuous 

 spike-like spine on its proximal end. No upper arm. plates or tentacle 

 scales. Oral papillaB and arm spines few. 



Type species. Ophiostyracium trachyacanthum. 



This is another relative of OpMoscolex, but is at once distinguished 

 from that genus by the large radial shields and the spike-like disk 

 spines. 



OPHIOSTYRACIUM TRACHYACANTHUM, new species. & 



Disk 6 mm. in diameter; arms about 25 mm. long. Disk covered 

 with a thin skin, on which are scattered a few thin, indistinct scales, 

 the more conspicuous of which carry long, sharp spines. Radial 

 shields large, thick, three times as long as wide, rounded at the ends, 

 nearly or quite touching distally but diverging widely within. Each 

 shield carries near its proximal end a very large, sharp, spike-like 

 spine. Upper arm plates wanting. Interbracliial space below bare. 

 Genital slits very large. Oral shield rounded pentagonal, wider than 

 long, with disto-lateral sides concave. Adoral plates very large, 

 meeting broadly within, and separating oral shield from side arm 

 plates without; oral plates and oral tentacle pores conspicuous. 

 Oral papillae spiniform, three on a side and one at apex of jaw; distal- 

 most smallest, short, rounded, looking as though it arose from first 

 under arm plate, below oral tentacle pore. First under arm plate 

 roundish; succeeding plates tetragonal, with rounded corners, and 



a "0<f){o and arupaKiov, signifying a small spikr, in reference to the spike-like spines 

 on the disk. 



& Tjoajwf, signifying rough, and aKavOa, signifying spine, in reference to the rough arm 

 spines. 



