A. H. CLARK : THE CRINOIDS OF THE INDIAN OCEAN. 187 



nent narrow rounded median ridge; IBr.j pentagonal, nearly or quite twice as 

 broad as long, the lateral edges slightly shorter than those of the IBr;, making 

 with them an obtuse angle, with a naiTow rounded median ridge similar to that 

 on the IBr, in the proximal half; lIBr 2, with the rounded median ridge much 

 less prominent than on the IBr series. 



Twenty arms about 120 mm. long; first brachial small, wedge-shaped, twice 

 as broad as long exteriorly, almost entirely united interiorly; second brachial 

 considerably larger, irregularly quadrate, both usually with a trace of a rounded 

 median keel; third and fourth brachials (syzygial pair) oblong, half again as broad 

 as long; next four brachials oblong, twice as broad as long, with a low tubercle 

 in the proximal half of the median line ; following two or three brachials wedge- 

 shaped, the following triangular, about as long as broad; arm tips not preserved. 

 On the lower part of the arm traces of tubercles are found on alternate sides of the 

 median line ; the proximal third of the arm is somewhat compressed laterally, and 

 bears on either side a shallow lateral groove. The arms increase slowly in diame- 

 ter up to about the twelfth brachial ; from the fourth onward the brachials have 

 moderately projecting finely spinous distal edges. Syzygies occur between the 

 third and fourth brachials, again between the eighteenth and nineteenth (rarely 

 the seventeenth and eighteenth or twentieth and twenty-first), and distally at 

 intervals of from four to nine (usually six to eight) oblique muscular articulations. 



P^ 8 mm. long, slender and weak, with twenty segments, the first broad, 

 slightly wedge-shaped, about twice as broad as the length of its proximal edge, 

 produced distally into a high rounded carinate process; second segment longer, 

 half again as broad as long, bearing a large fan-shaped carinate process with a 

 scalloped or dentate distal edge ; third and fourth considerably less in diameter 

 than the second, slightly longer than broad with strong oblong carinate processes ; 

 following segments non-carinate, slowly increasing in length, becoming twice as 

 long as broad in the terminal portion ; after the second segment the pinnule is 

 rather sharply triangular ; in the distal half the segments project somewhat over 

 the bases of the succeeding segments at the angles of the prism, this increasing 

 toward the tip where the ends of the segments overlap all around and are more 

 or less spinous; P.^ 14 mm. long, slender, but stifiE, with twenty-one segments ; 

 first segment broad , about twice as wide as its proximal diameter, roundedly 

 carinate distally ; second segment wedge-shaped, about as long as the proximal 

 length, with a thin carinate process about twice as broad as high distally; third 

 segment one third longer than broad, strongly carinate distally, but the carination 

 not quite so high as that on the preceding segment ; fourth segment twice as long 

 as broad, carinate distally like the third; following segments about two and one 

 half times as long as broad, slightly longer in the terminal part ; the pinnule is 

 strongly stylif orm , the segments being more or less produced anteriorly at the angles 

 of the prism in the shape of a spine overlapping the bases of the succeeding seg- 

 ments ; the distal ends of the segments are somewhat prominent and finely spinous, 

 this becoming more pronounced distally; P3 15 mm. long, similar to P^, though 



