80 THE VOYAGE OF H.M.S. CHALLENGER. 



wider than inner, curved. Disk round, flat, and rather thick, covered with thin flat 

 scales and plates of various sizes, among which are six rounded primaries, separated 

 by single lines of small scales ; in the brachial space, just inside the radial shields, 

 there is a transverse row of larger rounded scales ; in each interbrachial space are 

 two separated plates similar to the primaries, and outside these, along margin of disk, is 

 a row of four connected plates. Radial shields conspicuous, pear-seed shaped, widely 

 separated by disk scales. Outside the radial shields is an arm comb of small, short 

 pointed papillae, a part carried on outer point of genital scale and a part on outer edge of 

 radial shield and on the scale between the radial shields ; besides these there is on the 

 outer edge of the first three upper arm plates a row of from three to five papillae. Lower 

 interbrachial space covered by regular rows of small, semicircular, overlapping scales, and 

 by the genital scales, which are longer than broad, and slightly wider without than 

 within, and sometimes carry on their free edge an irregular row of minute papillae. First 

 pair of tentacle pores have two very small scales on the outer edge, the rest have one on 

 each side. Three long, slender, cylindrical, sharp, tapering arm spines, situated close 

 together low on the outer edge of the side arm plates ; lengths to that of an arm joint 

 l - 2, '8, '6 : '6. Colour in alcohol, white. The upper arm plate comb is variable. The 

 tentacle scales easily drop off. 



One young, with a disk of 3 mm., differed in having the upper disk covered almost 

 entirely by the primary and the other large plates ; the intermediate disk scales were 

 just beginning to form. The radial shields were shorter, and the papillae above the arm 

 fewer. 



Kerguelen Islands ; 120 fathoms. Prince Edward's Island ; 85-150 fathoms (same 

 species?). Station 152.— February 11, 1874; Lit. 60° 52' S., long. 80° 20' E. ; 1260 

 fathoms ; diatom ooze. Station 146. — December 29, 1873 ; lat. 46° 46' S., long. 45° 31' 

 E. ; 1375 fathoms; globigerina ooze. Station 157.— March 3, 1874; lat. 53° 55' S., 

 long. 108° 35' E. ; 1950 fathoms ; diatom ooze. 



Ophiocten pallidum, Lym. (PI. IX. figs. 4-6). 



Ophioeten pallidum, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 102, pi. v. figs. 126-128, 

 1878. 



Disk covered with minute thin scales, among which appear very small, widely separated 

 primary plates. One minute tentacle scale. Three short, equal, slender arm spiues. 



(Type specimen from Station 160.) Diameter of disk 14'5 mm. Length of arm about 

 70 mm. Width of arm close to disk, without spines, 1*7 mm. Five short, blunt, ill- 

 defined mouth papillae on the side, and one larger at apex of jaw, like the three or four 

 teeth that stand immediately above it. Mouth shields much broader than long, bounded 

 on the outer edge by a wide curve and by a very wide angle within ; length to breadth 



