70 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



a 2 . No abactinal papulae on rays; mouth plates smaller. 



6'. Adambulacral combs with proximally five spines; no straight pedicellariae. 



microgenys Fisher. 



6'. Adambulacral combs with two or three spines; spatulate oral straight pedicellariae. 



nannodes Fisher. 



ANTELIASTER COSCINACTIS Fisher 

 Plate 29, Figures 1, la-le; Plate 35, Figure 6; Plate 36, Figure 4; Plate 37, Figure 3 

 Anteliaster coscinaclis Fisher, Ann. and Mag. Nat. Hist., ser. 9, vol. 12, 1923, p. 252. 

 Diagnosis.— Rays five, long, slender, flexible, very gradually tapered to a bluntly 

 pointed extremity; disk small; body wall rather thin; spinelets very small, close-set 

 alternating, on the rather large meshed skeleton, with small crossed pedicellariae; 

 abactinal papular areas irregular (in equivalent of about three series) ; about three 

 actinolateral series of regular, subquadrate meshes; two series of actinal plates; 

 adambulacral spinelets longer than any of the others, proximally four or three, then 

 two, in transverse series; large hand-shaped, unguiculate straight pedicellariae. 

 R 63 mm.; r 9mm.; R = 7r; breadth of ray at base, 7.5 to 10 mm. 



Description. — The abactinal surface has somewhat the appearance of that of a 

 deep-water Henricia, the pedicellariae and small spinelets standing in single file on the 

 narrow, very irregular skeletal ridges. The meshes are large, not at all uniform in 

 size, very irregular in form, and contain three to six papulae. The spinelets are quite 

 delicate, 0.4 to 0.5 mm. long, while the interspersed crossed pedicellariae are 0.27 to 

 0.3 mm. long. Usually there is but one spinelet to a plate, but since the plates them- 

 selves are small, the spinelets stand less than their own length apart, with usually one 

 or two pedicellariae between. The form of the spinelets is best appreciated from 

 figures. Both the marginal and actinal spines and pedicellariae are a little larger than 

 the abactinal, and the spines are tapered and pointed. In contrast to the abactinal, 

 the lateral and actinal papular areas form three (or two in smaller specimens) regular 

 longitudinal series, broken here and there by slight irregularity, like that of a clumsily 

 mended net. 



An analysis of the skeleton, of great importance for identification, reveals a 

 very irregular carinal series of three, four, or even five lobed plates, joined by one to 

 three intermediate ossicles. There are the equivalent of two dorsolateral series of 

 + or Y shaped plates, joined by elliptical intermediate ossicles, forming the very 

 irregular reticulum alluded to above. Then comes two series of +-shaped marginal 

 plates, the inferomarginals the more regular of the two, and between these and the 

 adambulacrals are two series of actinals, the inner not fully developed. Transverse, 

 elliptical ossicles join the three outer of these four series as shown in the figure. 

 The outer series of actinals continue to within 10 mm. of the end of ray, and the inner 

 series, varying on different rays, to well beyond the middle. 



The relatively long, slender, tapered, pointed adambulacral spines form a bristling 

 cheveux-de-frise on the furrow margin. The spines stand in transverse combs, four 

 on the first four or five plates, then three on the following six plates, then two for the 

 remainder of the ray. Of these, the inner is a little shorter and slenderer than the 

 outer, which is 2.5 to 3 mm. long. The second spine is slightly the longest, in the 

 combs of three and four. The external end of the first adambulacral plate is rather 

 widely separated from its vis-a-vis across the interradial angle. There are no small 



