206 



THE ATLANTIC. 



[chap. IV. 



Ilymenaster nobilis (Fig. 48) is 300 mm. in diameter from tip 

 to tip of tlie rays ; tlie arms are 55 mm. wide ; and, as in ILpel- 

 lucidus, a row of spines fringing the ambulacral grooves are 



Fig. 4S. —Hymenaster nobilis, Wyvii.le Thomson. Southern Sea. Half the natural size. 



greatly lengthened and webbed, and the web running along the 

 side of one arm meets and unites with the web of the adjacent 

 arm, so that the angles between the arms are entirely filled np 

 by a fleshy lamina stretched over and supported by spines, the 

 body thus becoming a regular pentagon. The upper surface of 

 the body, the disk, and the arms — all the surface except the 



