On North Facile Zoroasteridaj. 387 



XXXYl.—^Wth Pacific Zoroasteiidae •. By Walter K. 

 FlSHKK, Din-etor, llDjjkiiis Alariiie Station o£ Stautoid 

 Uuiveisity, Calitornia. 



Starfishes of the family Zoroasteridse are abundant on 



muddy bottom in deep water off the west coast of the United 

 State.-s, and form a very characteristic element of the fauna. 

 While the species are not especially numerous, individuals 

 ajiparently swarm in some localities, judging by the results 

 of dredge-hauls. 



In this paper one new species and three new subspecies 

 are briefly diagnosed. Keys to the west American species o£ 

 Zuroasttr and Mi/xoderma will serve, it is hoped, to designate 

 by contrast the characters of the new forms. A synopsis of 

 the genera of Zoroasteridse is included in order to present in 

 compact form our present knowledge of the status of these 

 groups. The anatomical details for which some novelty may 

 be assumed will be dealt with in more detail in a monograph 

 of Piiilippine and Moluccan sea-stars now in press. 



Further study of MyxodermOj first proposed as a subgenus, 

 has shown it to be very distinct fr^im Zoroaster. The 

 cai)ture by the 'Albatross' of large examples of Cuentidaster 

 uijvillii, not a great distance from the type-locality, has 

 thrown new light upon a genus which was based upon a 

 young and wholly inadequate specimen. Very small examples 

 of Zoroasterida3 are very different from the adults — in fact, 

 they sometimes differ from the mature specimens in characters 

 of generic importance ! To jjut the matter more concretely, 

 very young Zoroasttr has all the adambulacral plates sub- 

 equal [=rrognaster stage), which is true also of little 

 examples of Cneinidasltr. The latter lack also adradial plates, 

 the presence of which is about the only constant character 

 by which the adult can be distinguished from Mammaster, 



I have not seen a specimen of Prognaster. Perrier con- 

 fused the matter by publishing a second description with 

 virtually a second type, P. longicauda, which appears to be 

 a slender-rayed Zoroaster. 



Synopsis of the known Genera 0/ Zoroasteridge. 



a'. Dorsal surface not devoid of spines and not 

 covered with a smooth tough luembrane, 

 in sharp contrast to the spinous or squami- 

 ferous actinolateral re^pous. 



* Published with permission of the U.S. Commissioner of Fisheries. 



