102 ZOROASTERIDAE. 
DD.‘ Adambulacral plates with only one transverse series of actinal spines. ; 
E.® Abactinal surface with coarse spinulation and numerous big pedicellariae. .. .ophiurus. 
EE. Abactinal surface with fine spinulation and few inconspicuous pedicellariae. 
F2 Carinal plates at base of arm quadrilateral much wider than long; superomarginals 
similar but smaller... -: 2... 02 --2 esses oe see eli eine rere ackleyi adult. 
FF2 Carinal plates about as long as wide with lateral margins more or less deeply notched; 
superomarginals irregularly diamond-shaped with rounded angles, not much wider 
than long. : 
G2 Adambulacral furrows with few pedicellariae.........-.------++++++5 carinatus. 
GG. Adambulacral furrows with many pedicellariae.......... carinatus philippinensis. 
Zoroaster perarmatus,’ sp. nov. 
Plate 4, fig. 2. 
R = 98 or 125 mm.; r= 13 or 18 mm.; R=7-7.5r. Disk moderately 
large, not elevated above nor distinctly set off from rays. Primary plates 
distinguishable but not conspicuous and not at all swollen. Rays rather stout, 
the height at base equalling or exceeding the width, which is about .15-.17 of the 
length; rays tapering to a blunt tip, more slender in the larger specimen than in 
the smaller. Carinals moderate, wider than long, lateral margins narrowed 
by large papular areas. Adradial plates moderately well-developed, at least on 
basal part of arm, much longer than wide and nearly quadrilateral. Supero- 
marginals similar to carinals but only about half as large. Inferomarginals 
similar but somewhat smaller and relatively longer. Actinolaterals in four 
series (on basal part of arm), nearly square and closely joined, the papular pores 
being very small. There is no indication of imbrication among either the 
marginal or actinolateral plates. Madreporite 2-3 mm. across, rather prominent, 
close to disk-margin, surrounded by five or six spinelets. 
The great majority of the skeletal plates are more or less elevated at or 
near the middle into a conspicuous spine-bearing tubercle; the spine on the disk- 
plates, carinals, marginals, and adradials being stout and erect, .75-2 mm. 
high and .30—.90 mm. thick at base; on the actinolaterals the spine is often 
wanting but when present reaches a length of 5 mm. and a thickness of 1 mm. 
at base; in the smaller specimen, the spines are all erect, standing out at right 
angles to the plate-surface, but in the larger specimen, the actinolateral spines 
are all more or less appressed to the sides of the ray. On the disk-plates, carinals, 
adradials, and marginals, there are no secondary or miliary spines whatever, 
but there are numerous big pedicellariae, 1-2 mm. long. Actinolateral plates 
well-covered with rather stout spinelets, about ten to a plate; in alcohol, these 
spinelets are conspicuously sacculate but when dry the saccule disappears and 
‘ perarmalus = thoroughly armed; in reference to the extreme development of primary spines. 
