96 



PROF. P. M. DUNCAN ON THE OPHIURID.E 



The side arm-plates are small and flap-like, especially on the 

 lower surface of the arm. They contribute to the breadth of the 

 arm, and do not meet until near to the tip of the arm. There is a 

 small scale as a tentacle-spine. The number of spines varies in 

 different parts of the arm ; there are nine close to the disk and 

 then seven, six, and five, which is the usual number over the 

 greater part of the arm. A small glassy spine with side spinules 

 is seen on a few r plates near the disk, and it becomes a true hook 

 with four fangs at the seventh arm-joint, and the points of the 

 hooks, which are close to the tentacle-scale, look towards the disk. 

 The other spines are glassy and usually compressed, so that their 

 large lateral spinules are directed parallel with the arm. The 

 upper spine, which is the longest and slenderest, is needle-shaped, 

 sharp, and the spinulation is near the top and slight on the 

 stem. The next spines diminish in length, are long, compressed, 

 very spinulose near the top and less so on the stem. The spine 

 next to the hook is very compressed, and has long and sharp 

 spinules. Longest spine 3*5 millim. Breadth of disk 14 millim. ; 

 length of arm 140 millim. ; breadth of lower arm-plates near 

 the disk 1 millim. Colour of disk above dark purple, darkest 

 centrally and along the interradia and spaces bet/ween the radial 

 shields of a pair, relieved with smalt and white in splashes and 

 lines near the edges of the radial shields. 



Localities. King Island Bay, Elphinstone Island. 



Ophiothrix merguiensis, sp. nov. (Plate IX. figs. 14, 15 ; 

 Plate XI. fig. 31.) 



Disk nearly circular in marginal outline, covered with skin 

 in which there are minute scales, each bearing a short three- 

 thorned stump. Radial shields covered with a coarsely granular 

 skin, also with a few trifid stumps ; shields broadest at the 

 margin and projecting over the arm, separated from the neigh- 

 bouring pairs by a wide area covered with minute scales and 

 bearing thorny stumps ; a narrow line of the same structures 

 between the shields of a pair. 



Disk tumid beneath and covered in the interbrachial spaces 

 with crowded trifid stumps. Mouth-shields as broad as long, 

 broadly curved without and angular within. Side mouth-shields 

 small, triangular, meeting at a narrow point orally to the mouth- 

 shields, and not reaching aborally beyond the line of the mouth- 

 shields. Jaw-angles wide and short, perforated alongthe median 



