LINGTHORN. 137 



sionally, judging from fragments. The rays are from five 

 to seven in number, quite flat, and generally five times as 

 long as the disk is broad. Commonly they taper very 

 gradually ; but in some of the specimens from the east 

 coast they are broadest towards the middle, as represented 

 in Dr. Johnston's figure. The upper surface of both rays 

 and disk is covered with tubercles, each bearing a radiat- 

 ing circle of from six to eight sub-clavate papillose spines, 

 generally with from one to three short clavate spines in 

 the centre. These tubercles are very closely set, so as to 

 give the surface when not looked at near a very compact 

 appearance. Dr. Johnston says the circle of spines crown- 

 ing the tubercles can be expanded or closed at the will of 

 the animal. Towards the sides of the rays the tubercles 

 are arranged in regular transverse rows. The margins of 

 the rays are bordered by long rounded spines, which are 

 arranged in rows of four or five placed on regular trans- 

 verse ridges ; the uppermost spines are thickest. The 

 spines forming the immediate borders of the avenues are 

 long, slender, and angular, and are also placed on trans- 

 verse ridges. The madreporiform tubercle is extremely 

 lateral, almost marginal, and reticularly striate. The 

 suckers are placed in two rows in each avenue, and are 

 very long and cylindrical, not inflated as in the last genus. 

 The eyes are placed in the centre of a circle of spines at 

 the extremities of the rays. The colour is brick-red above, 

 varying in intensity ; the under surface and lateral spines 

 are straw coloured. 



This species varies in the number and proportion of its 

 arms. They are always either five or seven : I know of 

 no specimen as yet found having six arms. Those found 

 on the east coast have generally smaller tubercles on the 

 less tapering rays than the specimens from the west or 



