22 OPHIOPLAX LJUNGMANI. 



OPHIOPLAX gen. nov. 



Teeth ; no tooth-papillce ; numerous mouth-papilla?. Scaling of disk beset 

 with granulation. Arms long and rather stiff. Arm-spines few and smooth, 

 arranged on the ridges of the side arm-plates. One very large tentacle-scale 

 on the side arm-plate, and others, minute, on the under arm-plate. Two 

 long genital openings in each interbrachial space. 



The genus stands near Oj>liiocnida, but is distinguished by the numerous 

 mouth-papillae arranged as in Ophiura, and by the singular tentacle-scales. 



Ophioplax Ljungmani sp. nov. 



PI II. f. 04, 25. 



Special Marks. — Interbrachial spaces below and margin of disk minutely 

 granulated ; upper surface finely scaled, and with small, separated radial- 

 shields. One large and three minute tentacle-scales. Arms pretty long 

 and rather stiff 



Description of an Individual. — Diameter of disk, G""' . Width of arm without 

 spines, LY"""-. Length of arm, GO"""-. Mouth-papillaj five on each side, and 

 one under and similar in form to the teeth. The papillae are flat and 

 crowded ; the one next the outermost much wider than the others. Mouth- 

 shields small, egg-shape, with the point inward ; length to breadth .8 : .7. 

 Side mouth-shields very small and narrow ; joining the side arm-plates with 

 their outer ends ; not meeting within. Under amn-plates rather wider than 

 long, with a curve without, an obtuse angle within, and re-entering curves 

 on the sides ; length to breadth, .7 : .8. Side arm-plates nearly meeting 

 below, but well separated above. Upper arm-plates much wider without than 

 within ; the outer side curved ; the lateral sides straight and sloping towards 

 the median line; length to breadth, .7 : 1.4. Disk finely scaled above, six 

 scales in the length of a mm., where they are finest. The margin and under 

 surface covered by a minute granulation, about sixteen grains in the length 

 of a mm. Eadial shields small, irregularly oval, widely separated by three 

 or four parallel lines of scales ; length to breadth, 1 : .4. Arm-spines three, 

 of nearly equal lengths ; slender, rounded, smooth, tapering ; the longest, 

 gmm. Qjjg very large, nearly oval tentacle-scale standing on the margin 

 of the side arm-plate ; and three minute ones arranged along the lateral side 

 of the under arm-jjlate. The tentacles are smooth and moderately stout. 



