On North Pacific Zoroasteride. 387 
XXXVI.—North Pacific Zoroasteridee *. By Watrer K. 
Fisuer, Director, Hopkins Marine Station of Pa ote 
University, California. 
STaRFISHES of the family Zoroasteride are abundant on 
muddy bottom in deep water off the west coast of the United 
States, and form a very characteristic element of the fauna. 
While the species are not especially numerous, individuals 
apparently swarm in some localities, judging by the results 
ot dredge-hauls. 
In this paper one new species and three new subspecies 
are briefly diagnosed. Keys to the west American species of 
Zoroaster and ‘Mywoderma will serve, it is hoped, to designate 
by contrast the characters of the new forms. A synopsis of 
the genera of Zoroasteride 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 Philippine and Moluccan sea-stars now in press. 
Further study of My«oderma, first proposed as a subgenus, 
has shown it to be very distinct from Zoroaster. The 
capture by the ‘ Albatross’ of large examples of Cnemidaster 
wyvillii, 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 Zoroasteridze are very different from the adults—in fact, 
they sometimes differ from the mature specimens in characters 
of generic importance! To put the matter more concretely, 
very young Zoroaster hag all the adambulacral plates sub- 
equal (=Prognaster stage), which is true also of little 
examples of Cnemidaster. ‘lhe 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 of Zoroasteridee. 
a’, Dorsal surface not devoid of spines and not 
covered with a smooth tough membrane, 
in sharp contrast to the spinous or squami- 
ferous actinolateral regions. 
* Published with permission of the U.S. Commissioner of Fisheries. 
