REPORT ON THE OPHIUROIDEA. 101 



(Type specimen from Station 165.) Diameter of disk 4 mm. Length of arm about 

 6 mm. Width of arm close to disk, without spines, 1 mm. Mouth papillae so closely 

 soldered as to form an almost continuous narrow line from side mouth shields to apex ; 

 on either side is a long curved one, followed by two shorter, and by a narrow spine-like 

 one at apex of angle. Mouth shield pentagonal, with an angle inward, longer than wide ; 

 inner lateral sides straight, outer lateral corners rounded ; length to breadth "7 : '5. Side 

 mouth shields large, swollen ; broadest and rounded within, where they meet, then taper- 

 ing outward along the inner lateral sides of the mouth shields. Under arm plates long 

 pentagonal, with an angle inward, lateral sides re-enteringly curved, outer side slightly 

 curved. Side arm plates large, thick, and swollen, meeting below and above ; upper 

 arm plates small ; first one diamond-shaped, and second triangular with sharp angle 

 inward and outer edge straight ; the rest are similar, but grow rapidly smaller. Disk 

 highly arched and rounded ; in the centre a large hexagonal primary plate, surrounded 

 by six others, much swollen, with inner and lateral sides nearly straight and outer edges 

 rounded ; these seven plates cover almost the entire upper surface of the disk ; in the 

 upper interbrachial space there is a rounded, much swollen marginal plate, and over the 

 arm two small, joined, scale-like radial shields. On the under surface, outside the mouth 

 shield, there are two large plates, the outer and larger one connected with the large 

 marginal plate. Genital scale long and wide, and composed of three pieces. Tentacle 

 scales, long, narrow, and curved, the one on the interbrachial side being semicircular, 

 while the other on the lateral side of the under arm plate is small and lip-like. Two 

 very short, blunt arm spines, placed low on the outer edge of the side arm plate. 

 Colour in alcohol, pale straw. 



A smaller specimen, with a disk of 2 mm., showed no special variations, except that 

 the radial shields were relatively larger and there were only six primary plates, which is 

 doubtless the normal number. 



Station 164.— June 12, 1874; lat. 34° 8' S., long. 152° 0' E. ; 950 fathoms; grey- 

 ooze. Station 165.— June 17, 1874 ; lat. 34° 50' S., long. 155° 28' E. ; 2600 fathoms; 

 red clay. Station 166.— June 23, 1874 ; lat. 38° 50' S., long. 169° 20' E. ; 275 

 fathoms; globigerina ooze. Station 218. — March 1, 1875; lat. 2° 33' S., long. 

 144° 4' E. ; 1070 fathoms ; globigerina ooze. 



Species of Ophiomastus not herein described. 



Ophiomastus secundus, Lym. (PI. XXXIX. figs. 14). 



Ophiomastus secundus, Lym., Bull. Mus. Comp. ZooL, voL v., part 9, p. 218, pi. ii. figs. 16-18, 

 1878. 



West Indies. 339 fathoms. 



(ZOOL. CHALL. EXP. — PART XIV. — 1882.) O 14 



