THE OPIIIURIDiE. 



175 



A 



First ventral plate large^, with outer edge curved, inner sides concave. 

 Those beyond in contact far out on the arm (to the end?), but only the 

 two-three inner ones have the inner angle truncated, the rest have an 

 obtuse antrle within. The outer edge is curved, farther out usually with a 

 little re-entering curve in the median line, inner and outer laterals re-enter- 

 ingly curved, outer corners a little rounded. The inner ones are about 

 equally broad and long, farther out they are distinctly longer than broad. 

 Side arm-plates with prominent spine-ridge ; there is a little naked space 

 separating those of each two adjoining joints, but it is not very distinct. 

 Dorsal plates rhomboidal or triangular with outer edge curved; they are in 

 contact more or less far out on the arm; in this respect there is some 



variation. Arms not knotted. 



Disk densely covered with long, slender smooth spines, which end in 

 three long thorns (Fig. 8), c. 1 nun. long. Mostly the outer end of the 

 radial shields is uncovered ; they do not form ridges. Ventral side of 

 the disk 'covered by spines only along the margin, on the inner part the 

 delicate overlapping scales are uncovered. Genital scales not distinct. 



Five delicate, translucent, finely thorned arm-spines; the second from 

 above is the longest, about as long as l-|-2 joints, those below gradually 



length of the 



spmes 



does 



shorter, about as long as one arm-joint. The 

 not greatly diminish on the inner half of the arm; they do not form a 

 continual series over the dorsal side of the first free joint. The first one to 

 three pairs of pores have two elongated tentacle scales, those beyond one, 

 rather large, pointed, which is however not so large as wholly to cover the 

 tentacle pore. 



4 



Color in alcohol : brown. 



Stations 3425, 680 f., and 3430, 852 £; one specimen from each. 



t 



53. Ophiacantha paucispina n. sp 



Plate XVIII. Figs. 1-4. 



Diameter of disk, 18 mm. ; width of arm close to disk, 3 mm. ; length of 

 arms about four times the diameter of the disk. 7-8 rather thick, small, not 

 pointed mouth papillce on each side of the elongated mouth angle ; that on 

 the apex not much larger than the rest. They are often rather irregularly 

 arranged ; sometimes the outer one is apart from the rest, sometimes there 

 are more papillce crowded at the apex. Mouth shield broader than long, 



