A. H. CLARK : THE CRINOIDS OF THE INDIAN OCEAN, 197 



increasing in length, becoming squarish on the fifth or sixth and half again or 

 nearly twice as long as broad on the eighth or ninth ; next three or four segments 

 similar, the length then very slowly decreasing, the segments in the middle of the 

 cirrus being squarish and those in the distal part about twice as broad as long : 

 eighth, ninth, or tenth a transition segment ; shortly after the transition segment, 

 the median portion of the distal dorsal edge of the segments begins to become 

 prominent; this very slowly increases in height, arising from progressively more 

 and more of the dorsal surface of the segments, which become progres sively 

 more and more carinate, so that in the terminal torty-five or fifty the dorsal sur- 

 face is produced into a sharji thin keel, straight in front, convex posteriorly, the 

 outer edge parallel with the median line of the cirrus, in height equal to about 

 one third of the lateral diameter of the segment which bears it ; opposing spine 

 small and blunt, arising from the entire dorsal surface of the penultimate seg- 

 ment, the apex subterminal or central, in height equal to about one third the 

 diameter of the penultimate segment ; terminal claw small, about equal in 

 length to the penultimate segment, stout and moderately curved. The cirri are 

 rounded in the basal third, subsequently becoming strongly compressed laterally 

 and, when viewed from the side, somewhat broader. 



Ends of the basal rays visible as dorsoventrally elongated tubercles in the 

 angles of the calyx ; a deep and narrow cleft is seen between the radials and the 

 centrodorsal ; radials very narrow, convex proximally, concave distally, with a 

 small sharp tubercle in the median part of the proximal border ; IBrj about 

 three times as broad as long, the proximal border convex, the distal concave, in 

 close lateral apposition and extending rather well up into the angles of the 

 calyx ; the lateral edges are more or less denticulate, and there is a low, though 

 sharp, serrate median keel ; IBr.^ slightly longer than broad, shield-shaped, the 

 posterior border produced into a rounded projection incising the IBr, , the ante- 

 rior edges concave, the anterior angle somewhat produced, the lateral edges 

 somewhat denticulate ; it bears a sharp serrate median keel in the proximal two 

 thirds ; IIBr 4 (3+4), rarely 2, strongly convex dorsally, in close lateral apposi- 

 tion and sharply flattened like the IBr series, the lateral edges produced and 

 strongly denticulate; IIBr 3-|-4 (syzygial pair) centrally constricted with the 

 lateral angles produced as in the other species of the genus. 



Twenty arms 115 mm. long; first brachial short, slightly longer exteriorly 

 than interiorly, interiorly united, somewhat incised by the second which is nearly 

 twice as large and has a rounded posterior projection ; these two brachials, like 

 the IBr , and j, have a shghtly marked median carination; third and fourth 

 brachials (syzygial pair) not quite so long as broad, somewhat constricted cen- 

 trally ; next five or six brachials almost oblong, about twice as broad as long, the 

 surface rather strongly concave, then becoming wedge-shaped, and soon trian- 

 gular, nearly as long as broad, and after the middle of the arm wedge-shaped 

 again and about as long as broad. The arms are at first evenly rounded dor- 

 sally, but after the basal third tlie\? gradual!}' become comiDressed and more 



