272 BULLETIN OF THE 



its color in alcohol suggests that it lives also in shallow water, although now 

 i'ound for the first time in 69 tatlujins. 



Ophiobyrsa hystricis sp. nov. 



Plate VIII. Figs. 120-123. 



Special Marks. — At apex of mouth-angle two or three large, peg-like mouth- 

 papilla;; and two or three others much smaller, on either side, arranged in a 

 line which runs high up on the side of the angle. Five slim, glassy arm-spines 

 covered with skin. 



Description of an Individual.— 'Dianwter of disk 20 mm. Length of arm 

 187 mm. Wdith of arm near disk 5.5 mm. Height of arm 3 mm. The 

 somewhat long and narrow mouth-angle bears at its end a pair of stout, peg- 

 like papillae, and sometimes a tliird standing above them; on either side of the 

 angle, considerably above its lower edge, is a Hue of tliree similar l)ut much 

 smaller papillae. Mouth-shields and side mouth-shields entirely hidden )iy 

 skin, as are the plates (jf the arm. On removing the skin, the under arm- 

 plates are seen to Ije about 1 mm. long and .S([uarish, with outer corners cut off. 

 Side arm-plates like ridges, tapering at both ends, and with their lower end a 

 little inserted between the under plates. There is nothing to represent upper 

 arm-plates except two small nodules, one on each side of the median line. 

 These are homologous with tlie double row of spine-bearing tubercles found iu 

 0, rudis. Disk thick and swollen, and covered by a tough skin; its upper 

 surface is sparsely set witli very short spines, more numerous and longer over 

 the region of the radial shields, but all covered and obscured by the disk-skin. 

 Genital openings large, and nearly extending to margin of disk. Five slendei", 

 slightly rough, glassy, nearly equal arm-spines, ab(nit as long as one and a half 

 arm-joints. They are covered by thick skin. Very large fleshy tentacles, but 

 no tentacle-scales. Color in alchol, pale straw, with yellow tentacles. 



"Porcupine" Expedition, 18G9, Station 65, northwest of Shetland Islands, 

 345 fathoms, water 1°.7 Cent. 



This is the species mentioned by Sir Wyville Thomson on page 123 of the 

 " Depths of the Sea." It comes from tlie " cold area," where the sea is at or 

 below the freezing point of fresh water; Avhereas the three other species, 

 0. rudis, 0. serpens, and 0. Perrieri, from Australia and the West Indies, in- 

 habit much warmer water. By its small ])apilhc on the sides of the mouth- 

 angles this species differs from the typical Ophi(jbyrsa and approaches Ophio- 

 scolex; the joints of the arm-bones are, however, essentially as in Ophiobyrsa. 



Ophiomyxa tumida sp. nov. 



Plate I. Figs. 1-3. 



Special Marks. — Four or five slunder, tapering, sbt^ditly rough arm-spines. 

 Only a trace of upper arm-])lates. Radial shields small and not bedded iu a 

 cluster of scales. A single marginal line of small plates round the disk. 



