38 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



spine to a plate; in having a decidedly larger terminal plate, and a large pedicellaria 

 on the second (from furrow) adambulacral spine. 



Description. — The carinal ridge is carried to center of disk, the central, radial, and 

 basal plates of which bear a stout spine similar to those on the ray. All the plates 

 are perceptibly convex and are covered closely with papilliform blunt pulpy spinelets 

 like those of the rays. The pedicellariae are few and only a trifle longer than the 

 spinelets. Papular pores and papulae (single) very inconspicuous. 



The ray slopes off rather steeply from the carinal ridge like the roof of a house; 

 there is a perceptible angle between this dorsolateral surface and the slightly convex 

 or rounded lateral surface. Each carinal plate is convex, and the series as a whole 

 forms a ridge rising above the general level. Carinal spines robust, somewhat 

 swollen and furrowed, bluntly pointed to subtruncate. The adradial plates are 

 fairly well exposed and a few at the base of the ray bear a conical spine 2.5 mm. long. 

 Supermarginal spines robust but slenderer than the carinals, tapering, pointed, 

 about 2.5 to 3 mm. long, normally bristling as in fulgens. Below these is a longi- 

 tudinal series of similar inferomarginal spines, then four series of sharp actinolateral 

 spines, those of the two upper series being the longest. The fourth series extends 

 only a short distance; over the greater part of the ray there are either three or two 

 series only. The general surface of the plates is covered with close-set pulpy papilli- 

 form spinelets which are contiguous and completely hide the surface of the plates. 

 These are much thicker than the sheathed spinelets of Z. ophiurus from the same 

 station and show evidence of having been slimy in life. When dried, the calcareous 

 part is seen to be very delicate and sharp and 0.6 to 1 mm. long. The spinelets 

 then appear to be well spaced. The carinal plates carry upward of 50 and the 

 adradials about 15. The pedicellariae are fairly slender, evenly tapered, a trifle 

 longer than the spinelets, rather few and inconspicuous. They stand near the 

 single papulae, on both dorsal and lateral surfaces. 



The skeleton of the ray is very compact and is characterized by exposed adradials, 

 smaller than the superomarginals. (See pi. 13, fig. 2.) The carinals are rather long 

 with two short rounded lobes on each side. To 10 carinals at base of ray there are 

 19 adradials and 19 superomarginals ( = 35 mm.). In a specimen of Z. ophiurus 

 from the same station, to 10 carinals there are 14 adradials and 14 superomarginals 

 ( = 26 mm.). The carinals are thus bigger in actinocles, for in a space of 35 mm. in 

 ophiurus there are exactly the same number of adradials and superomarginals as in 

 actinocles. In the latter the adradials are much more exposed and thus appear to 

 be larger than in ophiurus. In actinocles the lowest or fourth series of actinolateral 

 plates extends only a short distance (about 22 mm., or one-sLxth the length of ray), 

 whereas in ophiurus they extend upon the outer part of the ray and bear spines. In 

 actinocles the third series extends two-thirds the length of ray, and the second series 

 to within about 20 mm. of the tip. If a cleaned ray of actinocles is compared with one 

 of ophiurus of the same size, the larger actinolateral field of the latter is at once very 

 evident. At the base of the ray in ophiurus the plates of the first two actinolateral 

 series are quite as large as the inferomarginal plates while those of the third series 

 are about two-thirds as large. In actinocles only the plates of the upper, or first, 

 row are as large as the inferomarginals, and that only at the very base of the ray, for 

 after the sixth or seventh plate of the series they become smaller than the infero- 



