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



Ophioceramis (I) clausa, Lym. (PI. XL figs. 4-6). 



Ophioceramis (?) clausa, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 124, pi. vl figs. 

 161-163, 1878. 



Four arm spines, the two upper sleuder and tapering, the two lower stout and blunt. 

 A great marginal scale, which occupies also most of the lower interbrachial space. 



(Type specimen from Station 170.) Diameter of disk 4 mm. Length of arm about 

 18 mm. Width of arm without spines 1*2 mm. Three short, stout, pointed mouth 

 papillae, well separated on each side, with one larger and spearhead shaped at the apex of 

 angle. Mouth shields broader than long, transverse diamond-shape, with outer angle 

 indented; length to breadth "6:1. Side mouth shields very large and wide, somewhat 

 longer than wide, square without, meeting broadly within, and there forming a deep angle. 

 First under arm plate broader than long, rounded ; the rest are widely separated, twice as 

 broad as long, with outer edge nearly straight, a very obtuse angle or weak curve within, 

 and a small re-entering curve on the lateral sides. Side arm plates stout, flaring a little 

 outward where they form the spine ridge, meeting broadly above and below. Upper arm 

 plates broader than long, wide fan-shape with an angle inward, somewhat swollen, making 

 the arm high and rounded. Disk round and fiat, covered with thin, flat, angular scales 

 arranged symmetrically ; central primary plate pentagonal, surrounded by five others 

 rounded hexagonal and somewhat smaller ; interbrachial spaces filled by three large scales, 

 the two inner ones four-sided, the outer one rounded and lying on the margin, showing little 

 above, but beneath occupying the whole interbrachial space except two small scales 

 outside the mouth shields. Radial shields regular, longer than broad, wide without, 

 coming by curved sides to a point within, where they are separated by a small triangular 

 scale, but are joined for the rest of their length ; they, as well as the other disk scales, 

 bear a few microscopic tubercles. Four arm spines ; the two upper thin and tapering, 

 and nearly as long as an arm joint ; the two lower shorter, stouter, and more blunt ; 

 towards tip of arm there are three, the upper long and slender, as long as two joints ; 

 the second similar, but shorter ; and the lowest very stout and somewhat curved. One 

 very small rounded tentacle scale, on the first two pairs of tentacle-pores ; beyond there 

 are two. Colour in alcohol, pale brown. 



Station 170.— July 14, 1874 ; lat. 29° 45' S., long. 178° 11' W. ; 630 fathoms; rock. 

 Station 171.— July 15, 1874 ; lat. 28° 33' S., long. 177° 50' W. ; 600 fathoms; rock. 



Ophioceramis (?) obstricta, Lym. (PI. XL figs. 1-3). 



Ophioceramis (?) obstricta, Lyin., Bull. Mus. Comp. Zool., vol v., part 7, p. 124, pi. vi. figs. 164- 

 1C6, 1S78. 



Five short, nearly equal, blunt, tapering arm spines. Radial shields separated in the 

 brachial spaces, but touching in the interbrachial. 



