244 BULLETIN OF THE 



Ophiocten Patterson! sp. nov. 



Plate IV. Figs. 46-48. 



Special Marks. — Longest arm-spine as long as one and a half arm -joints. 

 Disk covered above irregularly with larger and smaller scales. Arm-comb 

 feeble. One wide mouth-papdla on each side, and two spiniform farther in, 

 with one at apex of mouth-angle. 



DescrijAion of an Individual. — Diameter of disk 9.5 mm. "Width of arm 

 close to disk 1.6 mm. A very wide papilla at outer corner of mouth-angle, 

 and two spiniform within it, on either side, and one or two at the apex. Three 

 slender, spike-like teeth. Mouth-shields rounded squarish, as broad as long, 

 with an ill-marked angle within ; length to breadth, 1.2: 1.2. Side mouth- 

 shields veiy narrow, of equal width, meeting fully within. First under arm- 

 plate large, about as broad as long, of a rudely rhomboidal form, with a 

 rounded angle outward ; the rest are much wider than long, with a rounded 

 angle without, a little peak within, and sharp lateral corners. Side arm-plates 

 slightly flaring outward, meeting broadly below, where they cover most of the 

 arm; separated above by the upper arm-plates, which are much broader than 

 long, and a little wider without than within ; length to breadth, .8 : 1.5. Disk 

 circular and flat on top, where it is covered with fine, thin scales, among 

 which appear numerous irregular plates, which form a continuous patch at the 

 margin. Radial shields small, irregular, and widely separated. Interbrachial 

 spaces below covered by a more regular imbricated scaling, and without plates. 

 Genital scales hidden, except their outer ends, just outside the radial shields, 

 which bear a feeble arm-comb of half a dozen or less minute papillae. Tentacle- 

 pores large ; the outer ones are i'urnished with a small scale, Avhich often is 

 lacking on the basal pores. Three very slender, tapering arm-spines, the 

 uppermost and longest one as long as one and a half or two joints. Color in 

 alcohol, pale yellowish gray. 



Station 344, Lat. 40° 1' N., Long. 70° 58' W., 129 fathoms, 1 specimen. 



Ophiomusium eburneum Lym. 

 Bull. M. C. Z., I. 10, p. 322, 1809. lU. Cat. M. C. Z.., VI., PL II. figs. 1, 2, 3. 



It happened strangely enough that the specimen originally described by me 

 was only half grown and aberrant, diff'ering from ordinary specimens somewhat 

 in the comparative thinness of the disk scales, but chiefly in the narrowness 

 of the arm, which was only 1.3 mm., while an average individual with a sim- 

 ilar disk (9 mm.) would have an arm 2 mm. wide. I found, however, one or 

 two whose arms were not much wider than those of the type. 



This species attains a good size. One with a disk of 15 mm. had arms about 

 50 nnn. long and 3 mm. wide. The radial shields were more elongated than in 

 the type, and there were three little arm-spines. 



