132 ECHINODERMS OF THE BRITISH ISLES 



Key to the species of Zoroaster known from or likely to 

 occur in the British seas. 



Arms moderately long, R = ca. G-12r, and rather stout; marginal 

 plates rectangular, leaving only very small and inconspicuous 

 spaces for the papulte between them. Tube -feet in four rows 

 nearly to end of arm . . 1. Z. fulgens Wyv. Thoms. 



Arms very long, R = ca. 16 r, and slender. Marginals obtusely cross - 

 shaped, leaving fairly large and conspicuous membranous 

 spaces for the papula? between them. Tube -feet in four rows 

 only in the proximal (ca. \) part of arms 



Z. longicauda (E. Perr.) 



1. Zoroaster fulgens Y^jY. Thomson. (Fig. 75.) 



(Syn. Zoroaster trispinosus Koehler ; Z. diomedece Verrill ; 

 (?) Z. Ackleyi Perrier.) 



Rays moderately long, rather stout, subcylindrical. Carinals 

 with a median elevation to which is attached a coarse, conical 

 spine. Upper marginals also usually with such a spine, and in 



Fig. 75. — Zoroaster fidgens, oral and dorsal side. Somewhat reduced. 



the larger specimens often some of the intermediate plates on the 

 arms, as also some plates on the disk, carry similar spines. 

 (These spines are easily rubbed off by rough handling in the 

 trawl or otherwise.) All the plates otherwise covered with small, 

 uniform granules, which carry short, membrane-covered spinelets. 



