100 



PROF. P. M. DUNCAN ON THE OPHIURID^ 



broadest near the adoral edge ; either connected by skin or not, 

 and then very closely placed. 



Upper arm-plates arched from side to side slightly, broad, 

 broader than long considerably, short, broadest without and 

 curved at the aboral edge, near the disk, or slightly trilobed. 

 Inner edge nearly straight or curved when the plates, as they 

 often do, become elliptical; sometimes the sides are narrow and 

 rounded off. Here and there a plate is split, but this condition 

 may not occur in some arms. Side arm-plates flap-like, broad below, 

 and not reaching over the upper arm until very far out. A 

 small jagged tentacle-scale ; tentacles large and long, crowded 

 with whorls of papillae. Spines, when the ectoderm is removed, 

 glassy with large bases, hollow. At the emergence of the arms 

 from the disk there are from seven to nine spines ; further out 

 there are six and usually five spines, the lowest being a double- 

 or triple-fanged hook, with some minute spinules on the reverse 

 side, which commences about the 12th joint or earlier, and then 

 it assumes a more spiny form. The next spine is small, short, 

 slightly compressed and very slightly spinulose ; the next is 

 longer and stouter, blunt at the top, compressed and oar-shaped 

 at the end, where the spinules are small and crowded ; serration 

 but slight on the edges of the compressed spine, and foramina 

 numerous. The second spine from above is the largest, longest 

 and broadest at the end, minutely spinulose at the top, and 

 slightly so for some distance down the shaft and then slightly ser- 

 rate ; perforations or foramina in several irregular rows. The 

 blunt broad-tipped spines with their comparatively small spinules 

 are distinctive. The first (upper) spine may be a small one and 

 resemble the others, or it may be longer and a plain hollow needle. 



Length of arms 12-14 times the diameter of the disk, which has 

 a diameter of 13*5 millim. Colour of the disk dull purple, rather 

 blue in tint, with a red tinge at the centre ; radial shields lighter 

 and with white background, splashed broadly with purple, low 

 stumps and the others also whitish. Beneath, the disk is white with 

 slight purple stains on the mouth-shields ; interbrachial skin dark. 

 Upper arm-plates purple or slate-colour, every fourth or fifth 

 plate of a darker colour, and hence a banded appearance is given. 

 Karely a narrow stripe of the same colour, but of a darker tint. 

 Lower arm-plates white within the disk, or with faint purple 

 splashes, further out with ;i purple border more or less entire, 

 with linei and doti of fche same colour on a while ground, tn- 



