KNOTTY CUSHION-STAK. 



129 



ventral surface is divided into four triangular spaces by the 

 tentacular avenues, which are fringed on each side with 

 a double series of smooth, blunt, short, and slightly com- 

 pressed processes or spines ; the triangular spaces are very 

 rough with enlarged granules and valvular openings ; but 

 there are no dilated bases for papillae, and the valvular 

 apertures are arranged in rows ; in the centre of each of 

 the compartments there is a large irregular opening. 

 When fresh, the colour is a bright red or scarlet, but on 

 keeping, the colour fades to a faint and dirty brownish 

 yellow. 1 '' 



Mr. Couch records the occurrence of one specimen of this 

 variety on the coast of Cornwall, in his Cornish Fauna. 



ipl^ 



K 



