REPORT ON THE OPHIUROIDEA. 151 



shape, nearly touching without, separated within by an oval of five scales ; length to 

 breadth, 2*5 : 1. Scaling on lower interbrachial space finer than that above. Three 

 rather slender, bluntly pointed, tapering, cylindrical arm spines, a little longer than an 

 arm joint, well up on the outer edge of side arm plates. Tentacle pores large, but 

 without a scale. Colour in alcohol, pale grey. 



Station 198.— October 20, 1874; lat. 2° 55' N., long. 124° 53' E. ; 2150 fathoms; 

 red clay. 



Amphileins tenuis, Lym. 



Amphilepis tenuis, Lym., Bull. Mus. Comp. Zool., voL vi., part 2, p. 35, pi. xvi. figs. 432-434, 

 1879. 



One minute tentacle scale. One mouth papilla on each side (sometimes broken in 

 two). Eadial shields short and wide, and joined for half their length. 



(Type specimen from Station 237.) Diameter of disk 4 mm. Width of arm close to 

 disk, without spines, "7 mm. One wide, pointed, somewhat bent mouth papilla high up 

 on each side of the mouth angle, and a jjair, short, thick, and rounded, at the apex. 

 Mouth shields small, twice as broad as long, of a transverse diamond shape, with rounded 

 angles. Side mouth shields three sided, short and swollen, wider without, tapering 

 rapidly within, where they scarcely meet. Under arm plates broad pentagonal ; with a 

 short angle within, outer side nearly straight, and laterals slightly curved. The first 

 plate is large and of a truncated wedge form. Side arm plates meeting broadly above 

 and nearly touching below. Upper arm plates twice as broad as long, of a nearly semi- 

 circular outline, with the curve inward. Disk flat and angular, covered with very thin 

 scales ; in centre of the disk is a rosette of six large ill-defined primary plates, each 

 nearly surrounded by minute scales. Radial shields short, wdde pear-seed shaped, joined 

 for the outer half of their length, narrowly separated within by a wedge of small scales. 

 Scaling on interbrachial space below much finer than that above. Three short, 

 cylindrical, bluntly-pointed arm spines. One minute, rounded tentacle scale, which 

 easily falls ofi". Colour in alcohol, faint greenish-grey. 



Station 237.— June 17, 1875; lat. 34°37'N., long. 140° 32' E.; 1875 fathoms; mud. 



OpMonema. 

 OpMonema, Ltk., Addit. ad Hist., part 3, 1869. 

 Disk, small, delicate, and a little puffed ; and having long, slender, even arms. Its 

 skin is quite naked, and its only solid parts are long, very narrow, parallel radial shields 

 above, and genital scales below. The mouth angles are short and small, as in Amphiura, 

 and bear four small papillse, whereof two are below the teeth. Four or five small, 

 regular arm spines. Two genital openings in each interbrachial space. 



