476 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39, 



except that when the animal is viewed laterally their outline is 

 more nearly triangular; the sides beyond this triangular inner half 

 curve inward (around the bridge supporting the ambulacra) and 

 then gradually outward again, so that their outermost diameter is 

 slightly greater than that of the base of the triangular tip; the out- 

 ermost border is more or less strongly concave (much more so than 

 in Hyocrinus), so that the outer margin is rather strongly bilobate; 

 there is a short spine in the center of each oral, and in the outer 

 half there are, irregularly disposed, two or three low flattened tuber- 

 cles, most of which are pierced by water pores. 



The anal tube, which is small and conical, rises just beyond the 

 bilobate outer margin of the oral; the whole anal area is covered 

 with perisomic plates, smaller on the anal tube and between it and 

 the oral than elsewhere, none of which are pierced by water pores. 

 The remaining interradial areas are completely covered by about 

 a dozen perisomic plates, of which four or five are usually much 

 larger than the others, irregular in shape and position, and bearing, 

 collectively, from a dozen to nineteen irregularly placed tubercles, 

 each pierced with a water pore. The sides of the wall or bridge 

 which supports the disk ambulacra are entirely covered by numer- 

 ous small subequal perisomic plates, entirely devoid of water pores. 



Arms. — None of the arms are complete; their normal length 

 appears to be between 55 mm. and 60 mm. ; the brachials are united 

 in syzygial pairs except the third, which has a muscular articulation 

 at either end ; the sides of the brachials are rather strongly concave, 

 so that the articulations and the syzygial sutures are prominent. 



The first pinnule (always on the fifth brachial) is 23 mm. long and 

 is composed of thirty segments, which, in a lateral view, are about 

 one-third longer than broad; the covering plates are large and 

 rounded-triangular, resting upon a calcareous band which is not 

 regularly differentiated into side plates, though in some cases the 

 oblong side plates may be fairly well indicated; the pinnule is much 

 compressed laterally, so that its lateral diameter is about half its 

 dorso- ventral diameter; it is large and practically uniform tlirough" 

 out; in its middle part its diameter is about equal to that of the 

 brachials at the same height; the following pinnules are similar, 

 but apparently first increase and then decrease gradually in size; 

 the second pinnule is 28 mm. long; the third pmnule is 26 mm. long, 

 with thirty segments; the fourth is 25 mm., and the eighth is 23 mm- 

 long, with twenty-three segments; the fifth pinnule on the right 

 posterior ray is replaced by an arm. 



Color (in life). — Pale sulphur yellow, the lower end of the stem 

 becoming brownish (F. M. Chamberlain). 



Type.—Csit. No. 27483, U.S.N.M., from Albatross station 5636. 



