A MONOGRAPH OF THE EXISTING CRENOIDS 277 



of the segments. The proximal three-fourths of the IBr 2 bears a prominent broadly 

 rounded median ridge which becomes higher proximally, forming a tubercle with a 

 similar ridge on the IBr, when that ossicle is visible. Similar rounded ridges occur on 

 the proximal portion of the second brachials and the distal portion of the first brachials. 

 The third brachial has a slight rounded median tubercle. The lateral edges of the 

 proximal brachials up to about the fifteenth are turned outward and produced into a 

 thin marginal flange, this feature becoming less and less marked distally and usually 

 not noticeable after the fifteenth. The elements of the IBr series and the first 5 or 6 

 brachials are sharply flattened laterally and are in very close lateral apposition. The 

 brachials, except for those at the bases of the arms, are rather strongly overlapping with 

 finely serrate distal edges. 



Syzygies occur between brachials 3+4, again in the vicinity of brachials 15+16, 

 and distally at intervals of from 5 to 11 (usually 5 to 7) muscular articulations. 



PI is 16 mm. long, tapering rapidly from a very broad base 2 mm. in width to 

 about the middle, then remaining slender and flagellate to the tip. It is composed of 

 35 or more segments of which the basal are very broad, much broader than long, and 

 those following become narrower and relatively longer to about the middle of the 

 pinnule beyond which point they are about as long as broad. The whole pinnule is 

 somewhat flattened, very much so basally. P 2 is 14 mm. long, similar to PI but not 

 so much expanded basally. P 3 is 12 mm. long, rather stiffer than, and not flagellate 

 like, P t and P 2 , with 20 segments of which the lower are evenly expanded, this expansion 

 increasing to the fourth or fifth, then gradually decreasing and ending at the eighth. 

 The segments as far as the fifth or sixth are about twice as broad as long, and those 

 succeeding increase in relative length, the comparatively slender segments following the 

 eighth being about twice as long as broad. P 4 and the following pinnules are similar, 

 but with the expansion of the lower segments more marked. Distally the basal expan- 

 sion gradually occupies less and less of the pinnule and at the same time the pinnules 

 become longer so that they have an increasingly long slender tip. After about P u the 

 basal expansion is not noticeable, the pinnules, though stout basally, tapering evenly from 

 the base to the tip. The distal pinnules are 15 mm. long with the first segment short, 

 slightly wedge-shaped, rather over twice as broad as long, the second similar but rela- 

 tively longer, and the remainder about half again as long as broad, becoming about 

 twice as long as broad distally. 



The color in life is ochre yellow, the cirri clear lemon yellow (W. K. Fisher). The 

 containing alcohol is stained either a deep orange red or emerald green. 



Notes. In the specimen from Albatross station 4180 with the arms 80 mm. long 

 both the elements of the IBr series are visible, and the ends of the basal rays are promi- 

 nent as vertically elongate tubercles in the angles of the calyx. The very broad char- 

 acter of the elements of the IBr series and lower brachials is marked, as is the eversion 

 of their edges, especially the lateral edges; but the proximal and distal edges as yet 

 have not taken on the crenulate feature characteristic of the fully grown. In this 

 specimen one of the IBr axillaries bears a regenerating pair of arms replacing an arm 

 lost, the IlBr series being 2, so that there are 11 arms. 



In the smallest specimen the radials are visible; these have a pronounced rounded 

 median ridge. The ends of the basal rays are prominent and project rather more than 

 in the specimen just noticed. The unusual broadness of the IBr series and lower 



