OPHIOBYRSA. 185 



than in 0. 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 = 34; 32. r = 4-5; 4. 



Distribution. Both sides of the Xorth 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., 3° 9' W., 203 fms. 'Porcupine ' Exp. (St. 74). 



/. 60° 0' N., 5° 13' W., 312 fms. < Porcupine ' Exp. (St. 82). 



2. OPHIOBYRSA. 



Ophiobvrsa, Lyman, Bull. M. C. Z. v. (1878) p. 131 ; id. Chall. Rep. 

 Oph.\l882) p. 243. 



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 hvstricis, Lyman, Bull. Mus. C. Z. x. (1883) p, 272, 

 pi. viii. figs. 120-122 ; Hoyle, Proc. Roy. Soc. Ed. xii. (1884) 

 p. 711 ; Bell, J. Mar. Biol. Assoc, i. (1890) p. 326 ; id. P. Z. S. 

 1892, p. 183, pi. xii. figs. 2 & 3. 



A verv large Ophiurid, Wyv. Thomson, Depths of the Sea, (1874) 

 p. 123. 



A large fine species, not unlike an Ophiomyxa. 



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. 



