A MONOGRAPH OF THE EXISTING CRINOIDS 217 



the ambulacral grooves and in the interarticular regions. The genital pinnules are 

 protected by irregular plates, and the ambulacra of the later pinnules have well-defined 

 side plates with alternating sacculi, which are also fairly abundant on the genital 

 pinnules. 



In alcohol the perisome is dark blackish brown, the skeleton whiter. 



Notes. — Prof. Torsten Gislen examined Carpenter's original specimen of this species 

 at the British Museum in 1925, and published the following notes upon it. The centro- 

 dorsal is discoidal, 11 mm. in diameter; it has a smaller radial and larger interradial 

 star dorsally, just as in certain Jurassic and Cretaceous comatulids. The cirrus sockets 

 are striated, with small lateral tubercles. The cirri are about XXXV, in 15-20 slightly 

 irregular columns. The arms are about 250 mm. long with a weak synarthrial carina- 

 tion. After examining the specimen in 1910 I wrote that this is a magnificent species 

 remarkable for its stoutness, and that it is well figured in the Challenger report. 



The specimen from Menado Bay, Celebes, is small with 17 arms; seven IIBr 2 

 series are present. 



In one of the specimens from Siboga station 297 the centrodorsal is large and 

 thick, truncated conical, 8 mm. broad at the base and 3.6 mm. across the stellate 

 dorsal pole, and 6 mm. high; on the proximal edge of the centrodorsal there are rounded 

 interradial ridges which are produced distally in a sharp angle between the proximal 

 portion of the proximal cirrus sockets, which meet below them; proximaUy these fork, 

 becoming prominent rather high tubercular processes on either side of the end of the 

 basal ray, which they much resemble; the surface of the stellate dorsal pole is slightly 

 concave in the center, with more or less marked radial and interradial grooves; the ends 

 of the rays of the star are not interradial but are somewhat twisted clockwise so that 

 they come under the left column of cirrus sockets in each radial area. The cirrus 

 sockets are arranged in 10 crowded columns of two each, with one in the center of a 

 radial depression and one on an interradial ridge. 



The cirri are from 55 to 70 mm. long with 28-31 segments, of which the first four 

 are short, those following gradually increasing in length to the ninth which, with the 

 following, is about half again as long as broad. The distal ventral edge of each seg- 

 ment projects slightly above the base of the succeeding segment. The last six or seven 

 segments taper very gradually so that the cirri, which throughout most of their length 

 are about 2 mm. broad, become on the penultimate segment 1.2 mm. broad. The 

 opposing spine is represented by a very slight terminal tubercle. The penultimate 

 and the distal third of the antepenultimate segment (sometimes the penultimate and 

 antepenultimate and the distal third of the segment preceding) are highly polished, in 

 contrast to the dull surface of the preceding ossicles. 



The ends of the basal rays are visible as prominent dorsoventrally elongated 

 tubercles in the angles of the calyx. 



The edge of the radials is just visible beyond the rim of the centrodorsal. The 

 IBr, are very short with parallel sides, distally incised by a rounded posterior projec- 

 tion from the axillary, laterally curving upward and meeting over the ends of the basal 

 rays. The distal inner angles are somewhat cut away. The median third of the dorsal 

 surface is swollen, forming a more or less evident laterally elongated large low rounded 

 tubercle. The proximal edge is slightly produced, especially in the lateral thirds, and 

 the distal outer angles are slightly swollen. The IBr 2 (axillaries) are rhombic, twice 



843803—50 15 



