98 ZOROASTERIDAE. 
figures of zea and wyvillii published by Alcock, Sladen, and Fisher. But as I 
have not seen a specimen of either of these last two forms, which Fisher intimates 
may be identical, I consider the number of valid species in Cnemidaster still 
uncertain. I think nudus is undoubtedly distinct from the East Indian forms 
but the three latter are certainly very closely allied. 
Key to the species of Cnemidaster. 
Spinelets of actinal surface with thin sacculation scarcely noticeable when dry, not covering the plates 
very closely. 
Distal earinals, and often marginals, with a central spine about as long as plate........... wyvilliz. 
Distal carinals and marginals unarmed, but often with one or more minute spinelets or elongated 
PT AMUES 85 <a ecw everce ove cre eel aha e 2s wee ee ss ch sree oxen PSI foge eke Re nudus. 
Spinelets of actinal surface flat, more or less squamiform, with heavy sacculation, closely covering the 
plates. 
Intermarginal papulae present; adambulacral ridge (on each alternate plate) with three stout spine- 
lets) 29. cece it Ste eine oho oe bw cowie d oo cee eM Se ae Oe eee eee squameus. 
Intermarginal papulae wanting; adambulacral ridge “bearing a row of three sabre-shaped spines 
and deep within the furrow.a slender'spinelet?? =. <. ome = eielete rele etter ieneteeeee zea. 
Prognaster. 
Perrier, 1891. Mem. Soc. Zool. France, 4, p. 259. 
Type-species: P. grimaldii Perrier, 1891. Loc. cit. 
Perrier, in his later, fuller account (1896. Hirondelle Stell., p. 22), says 
very emphatically that so far as he could see the adambulacral plates all extend 
equally into the furrow. This is so unusual a character for an adult zoroasterid 
that one can but suspect that Perrier has failed to examine the adambulacral 
margin with sufficient care. If he is correct, the genus is easily recognizable. 
The only known species was taken by the Prince of Monaco, near the Azores, 
in 1,568 fms. 
Pholidaster. 
SuapEN, 1889. Challenger Ast., p. 426. 
Type-species: P. squamatus SLADEN, 1889. Loc cit. 
Although Sladen published a short notice of this genus in 1885, he mentioned 
no species and hence the name must date from 1889. He never designated a 
type but Fisher (1919. Bull. 100 U. S. N. M., p. 484) has done so. The two 
known species were taken in the East Indian region: — squamatus in the Philip- 
pines in 100 fms. and distinctus in the Banda Sea in 140 fms. The ALBATROSS 
took squamatus at five stations in the Philippines in 108-218 fms. These are 
all remarkably slight depths for a member of this family. 
