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



angle ; the two lowest are smallest and are less flattened. Arm joints obscurely 

 indicated by the arm bones, whose outlines are seen through the skin. Arms broader 

 above than below ; covered with a thick skin, which, when partly dry, presents under 

 the microscope a minutely tuberculous surface. No tentacle scale on first arm joint ; 

 beyond this there is only one, short and peg like for some distance, sometimes as far as 

 the thirteenth joint ; after which there are two, still short, and cased in very thick bags 

 of skin ; on last third of arm the scale of the brachial side has become stout, thorny 

 ended, and much the longer (3 mm). Disk thick and angular, covered with thick skin 

 similar to that of the arms, and having interbrachial spaces re-enteringly curved. Eadial 

 shields high and narrow, diverging from the centre of disk to sides of the arms. The 

 genital openings are long, extending from upper edge of disk to mouth ring. Colour in 

 alcohol, uniform pinkish-brown. 



Station 232.— May 12, 1875 ; off Enosima ; lat. 35° 11' N., long. 139° 28' E. ; 345 

 fathoms ; sandy mud. 



Another somewhat smaller specimen had already two tentacle scales on the fifth joint. 



Ophiocreas abyssicola, Lym. (PI. XXXII. figs. 1-4). 



Ophioereas abyssicola, Lym., Bull. Mus. Comp. Zool., vol. vi., part 2, p. 64, pi. xvii. figs. 470-473, 

 1879. 



Arms scarcely as high as wide, about eight times the diameter of the disk. Skin quite 

 smooth, with radial shields scarcely indicated externally. Genital openings very short, 

 and situated near the inner interbrachial angle. 



(Type specimen from Station 241.) Diameter of disk 7 mm. Length of arm about 

 60 mm. Width of arm close to disk 1'7 mm. ; height of same 1*2 mm. Four or five 

 short, flat grains above the second mouth tentacle, on the sides of each mouth angle. 

 Seven stout, nearly equal teeth, shaped like a blunt spear head. On removing the skin 

 the small, irregular, rounded mouth shield, and large, longer than broad side mouth 

 shields, can be seen ; the latter are often broken. Under arm plates rather large, 

 rounded, as broad as long, closely soldered, and with vague outlines. Side arm plates 

 small, rounded, and swollen, closely joined with the under arm plates. Arm joints 

 recognisable through the skin. Arms rounded and slender, tapering very gradually to 

 the end. Disk flat and somewhat angular, not rising above level of arms, covered with 

 soft, moderately thick skin. Radial shields shorter and wider than in other species, 

 separated their entire length, and very thin and flat ; from the outside they are scarcely 

 indicated, and they do not meet in the centre. Two short, stout, bluntly pointed 

 tentacle scales, the lower one longer, and both nearly naked. Two very short genital 

 openings, about 5 mm. long, near inner angle. When the skin is removed the genital 

 plate and scale are seen, the plate being rounded, much longer than broad, tapering 



