OPHIOBYRSA. 135 
than in O. glacialis, Three arm-spines rather shorter than in the 
preceding species. One tentacle-scale. 
Colour said to be ** intense purpureus,” but in spirit quite white. 
R=384; 32. r=45; 4. 
Distribution. Both sides of the North Atlantic, as far south as 
23° 1' N., 83° 14’ W., 190 fms.; Norway, 64-767 fms. 
a. 59° 56’ N., 6° 27’ W., 363 fms. ‘ Porcupine’ Exp. (St. 54). 
b,c. 60° 14' N., 6° 17' W., 632 fms. ‘ Porcupine’ Exp. (St. 57). 
d, e. 60° 39' N., 8° 9' W., 203 fms. ‘ Porcupine’ Exp. (St. 74). 
7. 60° O'N., 6° 13’ W., 312 fms, ‘ Porcupine’ Exp. (St. 82). 
2. OPHIOBYRSA. 
Ophiobyrsa, Lyman, Bull. M. C. Z. vy. (1878) p. 181; a. Chall. Rep. 
Oph. (1882) p. 245. 
Mouth-armature consists of a set of spines at the angles, with a 
spine scattered here and there on the sides of the jaws. Disk 
covered with thick integument on which spines or spinous granules 
are feebly developed. Upper arm-plates reduced or absent; side 
arm-plates project and carry slightly roughened spines. No 
tentacle-scales. Very large bursal slits. 
1. Ophiobyrsa hystricis. 
Ophiobyrsa hystricis, Lyman, Bull. Mus. C. Z. x. (1883) p. 272, 
pl. viii. figs. 120-122; Hoyle, Proc, Roy. Soc. Ed. xii. (1884) 
p- 711; Bell, J. Mar. Biol. Assoc, i. (1890) p. 826; ad. P. ZS. 
1892, p. 185. pl. xii. figs. 2 & 3. 
A very large Ophiurid, Wyv. Thomson, Depths of the Sea, (1874) 
p. 128. 
A large fine species, not unlike an Ophiomywxa. 
Disk and arms flattened; skin of disk alone beset with spines, 
which are best marked on the radial shields; no spines on dorsal 
surface of arms. Radial shields narrow, wider without than within. 
Upper arm-plates represented by two vestigial plates, which do not 
meet in the middle line or touch their neighbours in front or behind. 
Five feebly roughened arm-spines, the uppermost the longest. Lower 
arm-plates tend to be square. The prominent bursal slit looks both 
downwards and outwards, and the outer portion is marked by a 
strongly curved lip. 
During life or in spirit the details are much obscured by the 
thick skin, which extends even on to the spines ; the skin in drying 
is apt to contort the specimen. 
Colour, in spirit, white ; dry, disk dark, arms lighter. 
R. ns 
185 2 
250 (or more) 16 
