REPORT ON THE ASTEROIDEA. 417 



the supero-marginal series, and sometimes on the intermediate abactiual series of plates ; 

 and one or more longer, delicate, tapering spines are usually present on each of the actinal 

 intermediate plates. 



Adambulacral plates small and quite within the furrow, and each alternate plate may 

 be produced and form a prominent ridge which extends far into the furrow (this character 

 probably only fully developed in the adult). Adambulacral armature consisting of several 

 elongate spines placed in single file along the edge of the ridge ; and one or two small 

 ciliary spinelets at the extreme edge of the plate. The intermediate non-prominent 

 plates bear only this small group of ciliary spinelets, and are devoid of spines on the 

 surface of the plate within the furrow. 



Madreporiform body small and inconspicuous, placed external to an interradial (basal) 

 plate. 



Anal aperture small, excentric, surrounded by a circlet of small ciliary spines. 



Small forficiform pedicellariae are present on the abactinal surface, one or occasionally 

 two being borne on the membrane in each mesh punctured by the papulae. Several small 

 forficiform pedicellarise are attached by membrane to the innermost spine of the armature 

 of the adambulacral plates. 



Ambulacral tube-feet small, with a fleshy terminal disk ; forming four rows. 



Remarks. — This genus was known hitherto only from the Atlantic ; a new form has, 

 however, been added by the Challenger from the Eastern Archipelago. All the species 

 are from great depths. 



Chorological Synopsis of the Genus Zoroaster. 



a. Geographical Distribution : — 



Atlantic : Five species between the parallels of 60" N. and 10' S. 



*Zoroaster fulgens, in the Faerbe Channel, off the coast of 

 Morocco, and the Sahara ; off the coast of North America ; and off 

 Pernambuco. Zoroaster longicauda, off the Azores, Senegal, and 

 the Sahara. Zoroaster diomedese, off the coast of North America. 

 Zoroaster ackleyi and Zoroaster sigsbeei, from the Gulf of Mexico, 

 the former off Montserrat and Santa Cruz, the latter off St Kitts, 

 and in lat. 28° 42' N., long. 88° 40' W. (The reference of Zoroaster 

 sigsbeei to this genus seems to me doubtful.) 



Pacific : One species between the parallels of 0° and 10° S. 

 * Zoroaster tenuis, off the coast of New Guinea. 



f$. Bathymetrical range : 38 to 2326 fathoms. 



Zoroaster fulgens, Zoroaster longicauda, and Zoroaster tenuis are confined 

 to the Abyssal zone. Zoroaster diomedese extends from the Littoral zone 



(ZOOL. CHALL. EXP. — PART LI. — 1888.) 53 



