REPOKT ON THE ASTEROIDEA. 75 



5. Dytaster sequivocus, n. sp. (PI. XXXVJ. figs. 5 and 6 ; PI. XXXIX. figs. 10-12). 



Rays five. E = 18 mm. ; r = 4 - 75 mm. R < 4 r. Breadth of a ray between the first 

 and second snpero-marginal plates, 4 "25 mm. 



Rays moderately long and robust, tapering gradually from the extreme base to the 

 extremity. Disk small. Interbrachial arcs rather angularly rounded. Abactinal surface 

 subplane, subject to slight inflation, with a central conical peak. Actinal surface plane. 

 Lateral walls rather high, rounded towards the abactinal and actinal surfaces. 



The paxillae of the abactinal surface are small and well-spaced, borne on comparatively 

 large basement plates, with a large, low, robust, tuberculose central eminence upon which 

 the crown is attached. The crown is composed of five to eight short, equal, papilliform 

 granules (occasionally with a tendency to the spiniform character), which are disposed in 

 a compact group, or radiate only very slightly apart. At the sides, near the base of the 

 ray, the paxillae show a tendency to be disposed in transverse series, more distinctly seen 

 in some specimens than in others. The paxillse are smaller on the flanks of the central 

 cone and on the outer part of the rays. 



The supero-marginal plates, sixteen in number from the median interradial line to the 

 extremity, are large, and form a well-defined border to the disk and rays. When viewed 

 from above their breadth is slightly greater than their length — this being an apparent 

 rather than a real dimension, caused by the arching or curvature of the plate toward the 

 abactinal surface. The median region of the plates is sbghtly tumid, but there is no 

 definite channel between adjoining plates as in Astropecten. The supero-marginal plates 

 bear a small, low, robust, papilliform tubercle near the upper margin, the largest being in 

 the median region of the ray. This tubercle is greatly aborted or absent altogether on 

 the innermost plate on each side of the median interradial line, and perhaps also at the 

 extremity of the ray. The surface of the plate is covered with small uniform papilliform 

 granules, rather widely spaced, except at the vertical margins of the plates. 



The infero-marginal plates correspond exactly to the superior series, which are directly 

 superposed. Their surface is covered with low papilliform granules, widely spaced on the 

 median area on the actinal region of the plate. The plates bear on the rounded angle that 

 unites the lateral and actinal areas of the test, or sometimes further upon the former, a 

 small, pointed, and more or less adpressed, spinelet, directed upward and outward, and 

 scarcely noticeable without a magniying glass. Up to the middle of the ray this spinelet 

 may be accompanied by one or two much smaller microscopic spinelets, usually placed 

 above it, and with a tendency to form a small compact vertical series or comb, adpressed 

 to the ray, on the upper part of the plate near the aboral margin. 



The adambulacral plates are elongate, but also rather broad on the inner half of the 

 ray, and the margin towards the furrow is convex. Their armature consists of : — (1.) A 

 furrow series of five or six small but rather long, cylindrical, obtusely tipped, delicate 

 spinelets, which radiate slightly apart and form a fan over the furrow. (2.) The actinal 



