236 AßT. 7. — I. IJIxMA : HEXACTINELLIDA, IV. 



Discoctasters (fig. 15), common. The six bosses present on 

 the central node. Prhicipals slender, at most 4 /^ thick ; about i 

 the length of the entire ray. Terminals fine, 3-6 in a gently 

 expanding tuft, with the minute terminal disc sliaped like a 

 pinhead. Diameter of the spicule, 1'28-160/a 



Basidictyonalia, as in S. sp. ß. 



In spiculation the specimen seems to resemble most closely 

 a young aS''. glaher, but differs not inconsiderably in the qualifica- 

 tion of the roughness of derraalia and in the size of oxyliexasters 

 as well as of discoctasters, — differences which at least render 

 doubtful the propriety of considering the specimen as of that 

 species. I have come to this view after carefully comparing it 

 with the smallest specimen (6 mm. high) of S. (jlaher in my 

 possession. 



RHABDOCALYPTUS F. E. Sch. 



Hypodermalia include pentactins in which the 

 paratangentials, when fully developed, bear series of 

 strong hook-like or prong-like spines. Veiled, but 

 in some cases the veil may be lost. 



Key to the known species. 



a Dcriualia, predominantly iientaclins, or pentactins and stunractins in nearly eijiial nuail ers. 



a^— Dibcoctaster not more tlian 100;). in diameter. 



a-.— Discoetaster wilii nearly straiglit terminals, wliicli diverge Imt slightly outwards 



in each tuft. Dermalia pentactins, occasionally stauractins 



R. damoni (Lambe). (Pacific coast of N. America). 



