PLATYCEIMDiE. 725 



are thickened around the facets, which project considerably and face almost 

 horizontally. Facets concave, semicircular, the surface crenulated at the 

 margin, their middle portions distinctly granular, the upper end provided 

 with shallow fossaj ; the distal faces directed obliquely outward and support- 

 ing a large covering plate at each side of the ambulacral passage. Costals 

 depressed pentagonal, five to six times as wide as long, the upper ano-les 

 obtuse. Distichals as long as the costals at the median line, those of the same 

 ray interlocking laterally with each other and with the palmars above ; the 

 axillary rhomboidal, the arm-bearing face directed obliquely to the side, the 

 opposite one horizontally. The palmars have the same form as the dis- 

 tichals, but are a little shorter. Plates of the succeeding orders more cuneate 

 and less regular in their arrangement; the axillaries upwards from the 

 fourth or fifth order decidedly triangular, while the plate below is but 

 little higher at one side than at the other, an arrangement which gives 

 to the upper part of the trunks a waving outline. The arms are set deeply 

 into the trunks, and their two or three proximal plates actually form part of 

 them, being suturally attached to the sides of four or five brachials, which 

 are truncated for their reception. The arms are directed obliquely upwards, 

 are biserial from the second plate, thicker at the proximal ends than at the 

 distal, and they are not very long, the lower ones not rising to the top of 

 the crown. The ventral covering of the appendages has not been observed 

 in this species, being hidden by the arms, but the transverse section shows 

 that it was similar to that of E. milkbrachiatus. 



Ventral disk composed of comparatively few, large, very heavy and con- 

 vex plates, among which the posterior oral occupies the central part. This 

 is surrounded by eight plates of nearly the same size, viz., the four other 

 orals, the proximal covering pieces of the posterior ambulacra, and two 

 plates, which, together with two others of equal size, form a protuberance 

 enclosing the anal opening. The covering pieces are large, but decrease 

 somewhat in size as they approach the appendages. There are but three 

 interambulacral plates in this species, transversely arranged, of which the 

 middle one, although less convex than the other disk plates, is larger than 

 any of them ; it is hexagonal, somewhat elongate, concave at the sides, and 

 it stands erect, being completely visible in a side view. 



Column similar to that of E. milkhmchiatus, but without nodes ; the long 

 diameter of the joints proportionally greater, and the twist more rapid than 

 in that species. The joints increase in length rather rapidly near the calyx, 



