A MONOGRAPH OF THE EXISTING CRINOIDS 445 



Diagnostic features. — The arms are about 40 (35-45 in fully grown individuals), 

 from 60 to 70 mm. in length. The cirri are very short, one-eighth or one-ninth of the 

 arm length, and are composed of 10-12 segments. 



Description.— The centrodorsal is rather thick discoidal, \vith the cirrus sockets 

 arranged in a single or partially double irregular marginal row. 



The cirri are XIII-XVIII, 10-11, 8 mm. long. 



The ends of the basal rays are visible as prominent tubercles in the angles of 

 the calyx. 



The radials project slightly beyond the edge of the centrodorsal. The IBri are 

 very short and bandlike, just in contact basally but with the greater part of their 

 lateral edges widely diverging so that they are separated by a broad shallow U-shaped 

 gap. The IBr2 (axillaries) are triangular, twice as broad as long, \vith the distal angle 

 very acute. The IIBr series are 4 (3 + 4), narrow, strongly rounded, and widely 

 separated. The IIIBr series are 2 (1+2). The IVBr series are 2 (1+2), developed 

 interiorly in reference to the IIBr series, but seldom present. 



The arms are 40 in number, from 60 to 70 mm. in length, and, with the pinnules, 

 resemble those of the other small species of the genus. 



The disk is naked. The mouth is central or subcentral, and the anal tube is 

 small, subcentral, or marginal. 



The color in alcohol is yellowish brown. 



Notes. — The specimen from the Andaman Islands, with no further data, is young, 

 with 28 arms. The IIIBr series are arranged in 1, 2, 2, 1 order. One of the derivatives 

 from a IBr axillary is undivided. 



With this there were dredged 2 arms from a fully grown individual, and a 10-armed 

 young with arms 23 mm. long. 



The specimen from Sebesi Strait has 42 arms 70 nun. long. The cirri are XIX, 

 10-12 (usually 11). 



The individual from north of western Java has 44 arms 80 mm. long. All of the 

 IIBr series are 4 (3 + 4). The cirri are about XX, 10-11 (usually 11). 



The largest individual from Siboga station 294 has 41 arms 100 mm. long. The 

 cirri are XXIV, 11-13 (usually 12), 10 mm. long. Of the others, which are very 

 small, 1 has 11 arms, and 2 have 10 arms only. 



The largest example from Siboga station 240 has about 36 arms which are about 

 75 mm. long. The cirri are composed of 9-10 segments, and are 9 mm. long. Of the 

 remainder, 1 has 11 arms 25 mm. long, 1 has 10 arms 45 mm. long, and the last has 

 10 arms 35 mm. long. 



The specimen from the Aru Islands recorded by Reichensperger has 32 arms 

 which are up to 70 mm. long. The U-shaped gap between the IBrj is clear and 

 conspicuous. The cirri are XIX, 10-12, from 7 to 8 mm. long. The second cirrus 

 segment is already somewhat longer than broad. The 3 following segments are 

 much longer than broad. In the succeeding segments the length decreases, but the 

 width increases somewhat. The color in life was deep black, with the tips of the 

 pinnules yellow. The color in alcohol is a uniform yellowish brown. 



The specimen from Siboga station 274 is young. It possesses 27 arms 55 mm. in 

 length. The cirri are XIII, 10-11, 8 mm. long. It appears to belong to this species and 



