A MONOGRAPH OF THE EXISTING CRINOIDS 



339 



shaped, about four times as broad as the median length, in the middle of the ami 

 becoming about three times as broad as long and at the arm tip about as long as broad. 

 When the arm. is viewed from the side the dorsal profile of the brachials, though approx- 

 imately straight, is seen to make a considerable angle with the axis of the arm so that 

 the profile of the arm as a whole is very strongly serrate. The prominent distal 

 edges of the brachials are very finely spinous. 



PI is 7 mm. long, slender and becoming very delicate distally, composed of 22 

 segments of which the first is much broader than long and the following gradually 

 increase in length, becoming about as long as broad on the eighth and twice 

 as long as broad terminally; the second-fifth have a high carinate process the 

 crest of which is parallel with the longitudinal axis of the segments; the first 

 has a similar but less-marked process; the sixth has a triangular keel that is proximally 

 as high as the keel on the preceding segment but runs to a point distally; the sixth and 

 following increase in width from the proximal to the distal end, making the latter very 

 prominent; the segments beyond the eighth are low triangular in section, with a more 

 or less rounded dorsal ridge. P 2 is 9 mm. long, with about 20 segments, similar to PI 

 but slightly larger with proportionately longer segments, these becoming about three 

 times as long as broad distally ; the second-fourth segments are carinate, like the second- 

 fifth in PI ; the fifth has a triangular keel like the sixth in PI ; the second and following 

 have the distal dorsal corner swollen and slightly produced. P 3 is 12 mm. long with 18 

 or 19 segments, much larger than the pinnules preceding; it tapers more rapidly 

 in the first four segments than beyond and remains rather stiff distally; the first 

 segment is irregularly triangular, not quite twice as broad as long, the second is 

 approximately oblong, about twice as broad as long, the third is slightly broader than 

 long, and the fourth is about one-third again as long as broad; the following segments 

 gradually increase in length, in the outer fourth of the pinnule becoming three tunes as 

 long as broad or even longer; the first segment has a dorsal tubercle; the second-fourth 

 bear a narrow straight edged carinsito process; the fifth has a narrowly carinate process 

 in the proximal half; on the second there is a slight projection of the dorsal distal 

 angle, which rapidly increases in size, becoming on the fourth and following a very 

 prominent, through narrow, projection of the distal dorsal angle involving about the 

 distal fourth of the dorsal edge, which is armed with fine spines. P 4 is about 7 mm. 

 long, with 13 segments, tapering more rapidly in the first four segments than subse- 

 quently, resembling P 3 but proportionately smaller with the projection of the distal 

 dorsal angles of the segments much less marked and the proximal segments only very 

 slightly carinate, P 6 is 6 mm. long with 13 segments, which become about as long as 

 broad on the fourth, and on the eighth and following from three to four times as long 

 as broad, with the distal dorsal angles slightly produced. The distal pinnules are 8 

 mm. long, with 17-19 segments, most of which are abo\it three times as long as broad, 

 smooth and cylindrical, without produced or spinous distal ends. 



Notes. The preceding description is taken from the specimen dredged by the 

 Siboga south of Salawatti. 



The characters of the type specimen dredged by the Challenger are, according to 

 Carpenter, as follows: The centrodorsal is hemispherical, with a denticulate rim. 

 The cirri are XX-XV, 25-30; nearly all the cirrus segments are longer than broad, the 

 fifth and sixth being the longest. The cirri are smooth dorsally, the outer segments 



