FEATUKE IN DEEP-SEA OPHIURANS. 7 



(fig. 6). Under arm-plates of a long axe-shape, much broader without than within, 

 with a widely curved outer edge, deep reentering curves on lateral sides, and a small an- 

 gle within. Side arm-plates nearly meeting below, widely separated above, having a fee- 

 ble spine-ridge on their outer margin ; before partly drying the specimen it is hard to 

 make out their outline. No upper arm-plates, so that the curious double arm-bones show 

 through the translucent skin (fig. 12). Disk, soft and delicate, slightly puffed, covered uni- 

 formly with scales so very thin that they can only be seen under the microscope by a 

 cross-light. No radial shields. Three nearly equal, sharp, somewhat flattened, arm-spines, 

 about as long as an arm-joint and a half. When cleaned with potash they appear as two 

 parallel spiculae united by cross-bars (fig. 15). At the ninth joint there still are three 

 spines standing near the outer margin of the side arm-plate, but at a large angle to the 

 arm, and just inside their base is a single minute parasol-spine, or pedicellaria, about 

 0.6 m.m. long ; and stouter and with a larger head than in 0. umbella. On the joints 

 beyond, there are no longer any common spines, but, instead, two close rows of parasol- 

 spines, three or four in each row (fig. 13). Tentacles large, long, smooth and not pro- 

 vided with scales. 



Color in alcohol, translucent bluish-white. 



"Challenger," Station 175, near Fiji Islands, 1350 fathoms ; 1 specimen. 



Here follow six new species, not included in my Prodrome of the " Challenger " Ophiu- 

 ridae, published in the Bulletin of the Museum of Comparative Zoology (Vol. V, No. 7 and 

 Vol. VI, No. 2). Of Ophiacantha, Ophiopeza and Ophiactis, there is one representative 

 each ; and there are three new genera, Ophiocymbium, Ophiochytra and Ophiambix, each 

 with a single representative. Among Ophiuridae and Astrophytidae the entire number 

 of new species brought home by the " Challenger " is 167 ; and of new genera, 20. 



Ophiocymbium-^ gen. nov. 



Disk flat and covered with delicate overlapping scales, without radial shields externally 

 visible. It overlies and is scarcely attached to the arms, like the borders of a Basque cap; 

 and there seem to be no genital openings. Arm-spines along outer edge of side arm- 

 plates. On jaw-plate, a tuft of small spines which correspond to teeth and tooth-papillae. 

 Mouth-papillae squarish and arranged in a close line. Tentacle-pores very large ; those of 

 the second mouth-tentacles set in a socket, much like the rest. 



Ophiocymbium cavernosum sp. nov. 



Special marks. Four arm-spines. Two or three disk-scales in the length of 1 m.m. 

 Side mouth-shields small and not meeting within. 



Description of an individual. Diameter of disk, 7.5 m.m. Arms broken, but appar- 

 ently about three times the diameter of the disk. Width of arm, without spines, 1.2 m.m. 

 At apex of mouth-angle is a boss-like jaw-plate bearing a cluster of four or five short, blunt, 

 irregularly placed spines, which correspond to teeth and tooth-papillae ; inside these, and 

 along the margin of the wide jaws, on either side, is a close hne of three or four flat, 

 squarish mouth-papillae, whereof the outermost stands on the margin of the socket of the 



1 'O^i^, a snake ; ia>/iptov, a flat cup. 



