OPHIOMUSIUM. 115 
meeting above and below. Upper arm-plates narrower than the 
arm, much longer than wide, bounded on all sides by gentle curves. 
Dise covered with thin, irregular, overlapping scales, and having in 
the centre a group of much larger rounded primary plates, 1 mm. in 
diameter. Below the scaling is similar but finer. Radial shields 
narrow oblong, or egg-shaped, small, separated by a narrow wedge 
of fine scales ; length to breadth, 2:1. Genital openings large and 
long, extending from mouth-shield to margin of disc. Three smooth, 
slender, tapering arm-spines, whereof the uppermost may be as 
long as two joints. Lengths, to that of an under arm-plate, 
2°5, 1:2, 1-2,: 1. One oval tentacle-scale of moderate size. 
‘Colour in alcohol, nearly white. 
*«* Porcupine’ Expedition, 1869, Station 42, south-west of Ireland, 
862 fathoms, water 4°°3 Cent.; 1 specimen.” 
I have never seen this species, of which I quote Mr. Lyman’s 
original description. 
AMPHIURID& (see p. 25). 
1. OPHIOMUSIUM. 
Ophiomusium, Lyman, Bull. M. C, Z. i. (1869) p. 322; td. Chall. Rep. 
Oph. (1882) p. 83. 
No tooth-papille ; teeth; mouth-papille confluent. Very large 
radial shields with intermediate plates form a stout covering to the 
disk; upper and lower arm-plates reduced or absent ; side-plates 
meet above and below; arm-spines very small. Tentacle-pores 
confined to area of disk. 
1. Ophiomusium lymani. 
Ophiomusium lymani, Thoms. Depths of the Sea, (1873) p. 174, 
figs, 82. & 33; Lyman, Chall. Rep. Oph. (1882) p. 90; Hoyle, Proc. 
Roy. Phys. Soc. Ed. viii. (1885) p. 151. 
Inner half of the disk occupied by five or six circlets of small 
irregular plates set round a single central and circular plate. 
Radial shields irregularly triangular, large, each member of a pair 
separated from its fellow, and from the adjoining pair by bands of 
about equal length formed by a few well-sized but not constantly 
regular plates. Five teeth; there are signs of the mouth-papille, 
when separate, having been seven in number. Mouth-plate shield- 
shaped, much wider behind them near the mouth, where it is pointed ; 
side-shields united in front of the mouth, longer than broad, irre- 
gularly oblong. Bursal slits rather short; the free part of the 
adjoining scale witha sharp edge. ‘Two large, irregularly quadrate 
plates outside the mouth-shield. The lower marginal plates swollen, 
few in number. Under arm-plates and single tentacle-scales on 
the first two arm-joints only. Upper arm-plates convex forwards, 
small, getting smaller, and disappearing altogether at about the 
12 
