A MONOGRAPH OF THE EXISTING CRINOIDS 451 



are developed externally in 2, 1, 1, 2 order. P, is about 10 mm. long, stiff like P 2 but 

 more slender, with about 14 segments, of which tbe first two are about as long as 

 broad, tbe next is balf again as long as broad, and tbe remainder are from two and one- 

 half to three times as long as broad. P 2 is 12 mm. long, with 10-12 segments, of which 

 the first is about as long as broad, the third is twice as long as broad, and those fol- 

 lowing are three times as long as broad. P 3 is not much more than half as long as P 2 ; 

 it is slender and slightly stiffened and is composed of 9 or 10 segments. P 4 and the 

 following pinnules are 4 mm. long and are slender and flexible. This specimen differs 

 from the type of monacantha from Mortlock Island in the greater length and stiffness 

 of Pi, and in the greater number of arms. 



The specimen from New Caledonia has 21 arms. The cirri have 19 or 20 seg- 

 ments. P 2 has 13 segments. 



The specimen from Sissie has 11 arms about 25 mm. long. 



The example from Batoe Ata is small, with 13 arms about 70 mm. long. 



The specimen from Beo, Talaut Island, is young, with 15 arms 50 mm. long. 



In the specimen from Siboga station 301 the 20 arms are 115 mm. long. The flat 

 dorsal pole of the centrodorsal is 2 mm. in diameter. The cirri are XXXIII, 20-21, 

 20 mm. long. P 2 is 15 mm. long with 15 or 16 segments, of which the fourth and fifth 

 are the longest. On the inner arms P 2 is 12 mm. long, though composed of the same 

 number of segments as on the outer. P 2 is relatively slender, much less spinelike than 

 usual, more flexible basally and becoming very slender distally; the three basal seg- 

 ments are about as long as broad, the fourth is about one-third again as long as broad, 

 and the remaining segments are elongated. It agrees with specimens from Ceylon, 

 with which it was directly compared. 



The specimen from Siboga station 250 has 14 arms 55 mm. long. The cirri are 

 11 mm. long. P 2 ic 6.5 mm. long, with 10-12 (usually 11) segments. 



All the specimens from Siboga station 89 are small. One has 15 arms 40 mm. long. 

 The cirri have 17 segments, of which the proximal are proportionately more slender 

 than in larger examples. P 2 is proportionately more slender than in the adults, is 

 slightly recurved, and is composed of 10 proportionately longer segments. P 3 re- 

 sembles the following pinnules. Another specimen has 20 arms 70 mm. long. The 

 cirri are about 16 mm. long, with 19 segments. P 2 is 8 mm. long, with 11 segments. 

 P 3 resembles P 4 . A third example has IS arms 65 mm. long. The cirri are 15 mm. 

 long, with 19 segments. P 2 is 9 mm. long, with 11 segments. Of the remaining 

 specimens three have 15 and four have 14 arms. In one of the latter P 2 has 12 seg- 

 ments. One individual, not included in the preceding enumeration, is small and 

 much broken. 



The figure published by Miss Boone of the specimen from Bali shows a typical 

 example of the form with slender pinnules. The arms are apparently about 115 mm. 

 long. 



The specimen from the Sunda Strait that Hartlaub found hi the Liibeck Museum 

 has 20 arms. The cirri are arranged in two rows on the centrodorsal. The arms are 

 slender. There are no IIIBr series. The lateral thickenings of the ossicles of the 

 division series are very characteristic. The color is remarkable in that, especially in 

 the lighter proximal portion of the arms, the ends of the brachials are much darker 



