MUSEUM OF COMPARATIVE ZOOLOGY. 59 



and obscured by skin. Radial shields small, ovoid, as long as broad, widely 

 sejDarated by a wedge of scales ; length to breadth 1.7 : 1.3. Genital openings 

 wide, and extending quite from the mouth-shield to the disk margin. Four 

 smooth, cylindrical, rather slender, blunt, tapering arm-spines, whereof the 

 lowest is as long as an arm-joint, the two upper ones as long as a joint and a 

 half, and the third intermediate. One rather large oval tentacle-scale. Color 

 in alcohol, gray, with arm inclining to straw. 



' Station 232, 345 fathoms, 124- specimens. Station 235, 565 fathoms, 

 1 specimen. 



Ophiacantha abnormis sp. nov. 



Plate XV. Figs. 411-413. 



Special Marks. — Mouth-angles elongated, bearing, toward the apex, 12 or 14 

 slender, pointed papillae. Six long, smooth, slender arm-spines. Disk sparsely 

 set with very short spines. 



Description of an Individual (Station 207). — Diameter of disk 11 mm. 

 Length of arm, which is very attenuated near its end, 73 mm. V\^idth of arm 

 close to disk, without spines, 2.5 mm. Mouth-angles elongated, having no 

 papillae on their outer part near the mouth-tentacles, but on their inner portion 

 bearing 4 or 5 slender, spaced papillae on each side, and a cluster of 3 or 4 at 

 the apex. Teeth wide and large, with a broad cutting edge. Mouth-shields 

 broad triangular, with a small peak on the outer edge, and blunt angle within. 

 Side mouth-shields short and extremely narrow, just meeting within. Under 

 arm-plates thin and sunken, pentagonal, with a broad angle inward, outer 

 edge straight, and deep re-entering curv-es on the lateral sides. Beyond 

 the third, they are separated by the side arm-plates, which meet below and 

 above and have a high, wide spine-ridge. Upper arm-plates triangular, some- 

 what swollen, with an angle inward, sharp lateral corners, and broad nearly 

 straight outer edge, which on the basal plates bears two minute spines. Disk 

 flat, having re-entering curves in the interbrachial spaces, and rather sparsely 

 set with minute, short, blunt spines, which are fewer below. The outer ends 

 of radial shields are exposed over the base of each arm. Genital openings long 

 and large, extending from mouth-shield to disk margin. Six long, slender, 

 smooth, cylindrical, tapering arm-spines, of which the two upper ones are as 

 long as two arm-joints, thence diminishing in length to the lowest, which is 

 about as long as half a joint. Pores large and tentacles very long ; on basal 

 ones are two scales, of a pointed oval shape ; on those beyond, only one. Color 

 in alcohol, straw. 



Station 207, 700 fathoms, 12-|- specimens. Station 210, 375 fathoms, 

 5 specimens. 



In its elongated mouth-angles, this species somewhat resembles 0. Jiirsutaf 

 but its arm-spines are smooth and in all ways different. 



