REPORT ON THE OPHIUROIDEA. 87 



under plate. Genital opening bounded by small close-set papillae, which extend upward 

 as a small arm comb. Side mouth shields small and short. Upper arm plates compara- 

 tively large, some of the basal ones inclining to hexagonal. Three or four small arm 

 spines. 



(Type specimen from Station 332.) Diameter of disk 11 mm. Length of arm 47 mm. 

 Width of arm near the disk 2 "5 mm. Mouth papillge six on each side, forming a close line, 

 and one larger one at apex of jaw. Mouth frames long triangular, quite large. Mouth 

 shields rounded triangular, with an angle inward ; length to breadth 1"5 : 1"5. Side mouth 

 shields short triangular, touching by their narrow ends within. First under arm plate 

 circular, very small ; the next three are furnished with tentacle scales, and are three- 

 sided, with an angle inward, and outer side curved ; the others are smaller and roughly 

 triangular, with an angle inward, and lateral sides curved. Side arm plates thick, and 

 meeting broadly below beyond the disk, but just touching above on the basal joints. 

 Upper arm plates long, diamond shaped, except at base of arm, where the outer and 

 inner angles are truncated. Genital scales very narrow, and so closely soldered to 

 surrounding parts as to be hardly distinguishable. Near inner end of genital opening 

 they bear a few square close-set papillae, as in Ophioglypha. Interbrachial space below 

 covered by ten or a dozen circular plates of irregular outline. Upper surface of disk 

 covered by long, rudely triangular, somewhat sunken radial shields, widely separated 

 their entire length by two or three large and several minute rounded plates ; the inter- 

 brachial space covered by a large circular marginal plate, with various smaller ones 

 within ; the central space within the radial shields by six rounded, sunken primary 

 plates, separated by about three rows of small scales. The entire surface is microscopi- 

 cally tuberculous. Three or four small cylindrical arm spines, situated well up on the 

 outer edge of the side arm plate ; they stand out from the arm, and the two middle ones 

 are largest. The second, third, and fourth under arm plates have, near their inner end, 

 small oval tentacle scales, one to each pore. Colour m alcohol, white. 



Station 83.— July 15, 1873; lat. 33° 13' N., long. 18° 13' W. ; 1650 fathoms; 

 globigerina ooze. Station 106.— August 25, 1873 ; lat. 1° 47' N., long. 24° 26' W. ; 

 1850 fathoms; globigerina ooze. Station 299.— December 14, 1875; lat. 33° 31' S., 

 long. 74° 43' W. ; 2160 fathoms (same species?) ; grey mud. Station 332. — March 10, 

 1876 ; lat. 37° 29' S., long. 27° 31' W.; 2200 fathoms; globigerina ooze. 



Ophiomusiwn corticosum, Lyni. (PL 11. figs. 13-15). 



OpMomusium corticosum, Lym., BuU. ]\Ius. ComiJ. Zool., vol. v., part 7, p. 110, pi. i. figs. 19, 

 20, 1878. 



Arms rather slender and tapering, cyhndrical, or but slightly wavy. Upper and 

 under arm plates persisting nearly to end of arm, but no tentacles beyond third or 



