REPORT ON THE OPHIUROIDEA. 203 



Ophiomitra plicata, Lym. (PI. X. figs. 7-9). 



Ophiomitra plicata, Lym., Bull. Mus. Comp. Zool, vol. v., part 7, p. 150, pi. viii. figs. 209-212; 

 pi. ix. figs. 233-235, 1878. 



Mouth papillae thick, spiniform. Arm spines five or six, stout and cylindrical. Outer 

 edge of under arm plates swollen and in large specimens turned down. Disk spines 

 stout and conical. 



(Type specimen from Station 205.) Diameter of disk 16 mm. Length of arm about 

 132 mm. Width of arm without spines 5 mm. Mouth papillae nine to each mouth 

 angle ; stout, spiniform, about equal, blunt. Teeth similar to mouth papillae, liut shorter 

 and flatter. Mouth shields small, as long as broad, with an irregular outline ; the outer 

 margin more or less thickened and curled downwards ; length to breadth, 2 : 2. Side 

 mouth shield broad, thick, and closely joined to the surrounding parts. Under arm 

 plates broader than long, broader without than within, separated by transverse depressions; 

 outer edge much thickened and curled downwards. Near end of arm they are wide 

 pentagonal, with an angle inward and the outer edge scarcely thickened. Side arm 

 plates slightly projecting near base of arm ; meeting narrowly below, and scarcely or not 

 at all above. Upper arm plates wider than long, irregular in shape, with a curved outer 

 side and an obtuse or irregular angle inward; length to breadth about 1"5 : 3 '5. Disk 

 (in alcohol) thick, rising well above the arms, and with a deep constriction and furrow in 

 each interbrachial space. Along the outer portion of the interbrachial edge of each radial 

 shield lie three or four plates, broader than long, and running diagonally outward ; the 

 rest of the disk is occupied by coarse, irregular, overlapping scales, beset with short, 

 stout, blunt, smooth, conical spines, which form an irregular line over the base of each 

 arm. Eadial shields sunken, and much longer than broad, narrowest within, rounded 

 and swollen without ; length to breadth, 5:2; separated by one or more narrow scales. 

 Five stout, cylindrical, rather short arm spines, tapering to a blunt point, with thorns on 

 all sides ; lengths to that of an arm joint, 37, 4, 3-7, 3, 2-5 : 2. Two-thii-ds out on the 

 arm, the second spine is much longer and attains a length of 8 mm. Tentacle scales 

 very stout, and thickened at the base ; pointed at the tip. On each of the first pair of 

 pores there usually are three, on the rest only one. Towards tip of arm the scale becomes 

 spiniform. Colour in alcohol, pale brown. 



Station 205.— November 13, 1874 ; lat. 16° 42' N., long. 119° 22' E. ; 1050 fathoms ; 

 grey ooze. 



Smaller specimens (Station 214) presented considerable variations: with a disk of 

 10 mm. the arm was 60 mm. long; there were only seven mouth papillae to each 

 angle ; the disk spines were thorny, the upper arm plates narrow ; the outer edge of the 

 under arm plates was somewhat swollen, but not curled down ; the first tentacle pore 

 had only one or two scales ; there were six comparatively long arm spines, whose lengths 

 to that of an arm joint were 5-2, 3, 2-8, I'B, I'S, TS : I'S. Other specimens (Station 



P 



