FEATURE IN DEEP-SEA OPHIURANS. 5 



partly dried specimen, is seen to stand on a small, delicate scale. No radial shields visible, 

 and there probably are none ; which, as in Ophiomyces, may account for the fact that the 

 arms are raised vertically, encircling the high disk like a fence. Three sharp, slightly 

 flattened, microscopically rough arm-spines nearly as long as a joint, standing near the 

 outer edge of side arm-plate, and on a low spine-ridge. At the ninth joint there appears, 

 on inner side of spine-ridge, find close to base of spines, a cluster of three or four 

 minute pedicellariae, scarcely 0.5 m.m. long. They are shaped like long-handled parasols, 

 or slender-stalked agarics (fig. 3) with a long shaft, surmounted by a disk divided into 

 symmetrical radiating flutings, and with a slight bulb at the l^ase articulated to a little 

 mamelon. They are glassy and translucent, and naturally are enveloped in a skin-bag 

 which, however, is easily stripped off, leaving them free, as shown in the figures. They 

 are found on all the outer joints, to the tip of arm. The tentacles are long, smooth and 

 translucent. The second mouth- tentacle has four flat scales similar to mouth-papillae. 

 The next two pairs have each two smaller scales, one on the side arm-plate, the other on 

 the under arm-plate. Each pore beyond has one long, spine-like scale on its inner edge. 

 " Challenger," Station 296, S. W. of Juan Fernandez; 1825 fathoms ; 1 specimen. 



Ophiohelus,^ gen. nov. 



Disk covered with a delicate, film-like scaling, without radial shields. Arm-bones com- 

 posed of two halves like curved bars, lying side by side, joined at their ends and enclosing 

 an oval hole. Mouth-papillae spiniform and arranged in a single row ; teeth similar ; 

 no tooth-papillae. On the outer joints of the arm, the true arm-spines cease, and are 

 replaced by two or more rows of minute spines or pedicellariae, which have the form of 

 a long-handled parasol. 



Ophiohelus umbella sp. nov. Plate I, figs. 4^10 and 16. 



Special marks. Parasol-spines long and slender ; about twenty altogether, arranged in 

 two or three irregular rows. Disk beset with minute spines. One small, sj^iniform ten- 

 tacle-scale. 



Deso^ijition of an individual. Diameter of disk 4.5 m.m. Arms long, slender and 

 gradually tapering ; in length about ten times diameter of disk. Width of arm without 

 spines 1 m. m. Mouth-angles covered by a thick skin (fig. 5), which must be removed to 

 see the hard parts, (fig. 6). The armature is all of short, sharp, spine-like papillae. The 

 small jaw-plate carries a cluster of from three to five, whereof the central one is longest, 

 and may be considered the lowest tooth ; then, outside these, there are three, somewhat 

 irregularly arranged on either margin, of which the outer one is longest, and may be con- 

 sidered as a tentacle-scale of the second mouth-tentacle. On taking off the covering skin 

 (fig. 6), there is seen a small mouth-shield as broad as long, three-sided, with an angle 

 inward and the inner sides curved. Closely soldei'ed to it are long, curved, side mouth- 

 shields which grow broader without and are closely united within. First under arm-plate 

 nearly as large as those beyond, shield-shaped, with inner lateral side a little turned down- 

 ward, and prolonged in an acute angle. From the third plate onward (fig. 7), the out- 



' 'O^ir, a snake; y'/.oc, a a broad-headed nail. 



