A MONOGRAPH OF THE EXISTING CRINOIDS 143 



the IIBr series. The produced and denticulate borders extend as far as the base of P 2 

 externally, and as far as the fifth or sixth brachial internally. 



The 28 arms are about 120 mm. long and in general resemble those of 0. gigantea. 

 The first two brachials are carinate. The brachials following have slightly everted and 

 finely spinous distal edges and the dorsal, but not the lateral, surface covered with very 

 numerous short fine spines. As the brachials become triangular the proximal edges 

 lose their eversion, while that of the distal edges becomes more recumbent and more 

 prominently spinous. The spinosity of the dorsal surface gradually becomes arranged 

 in definite lines forming a series of sharp, serrate, longitudinal striations. 



P D is 14-16 mm. long, comparatively slender as in the other species of the genus 

 and tapering very gradually to a delicate tip. It is composed of 28-30 segments all 

 of which are broader than long. The distal outer and distal inner margins of the seg- 

 ments are sharply and very prominently carinate, this carination being very spinous, 

 and on the proximal portion of the inner margin coarsely denticulate. A shallow con- 

 cave trough runs between these ridges. The proximal segments are more or less spinous 

 on the proximal (dorsal) surface. P P is like P D , but not nearly so long or so large. 



P, is 14 mm. long with 26 segments, similar to P D but more slender with the com- 

 ponent segments 6omewhat longer, with their produced borders more spinous, and with 

 the distal edges of the outer produced and spinous. P 2 is 8 mm. long with 17 segments, 

 much more slender than P! with longer segments distally which have more produced and 

 spinous distal edges. The following pinnules become progressively more slender with 

 progressively longer segments which have coarsely spinous distal ends. P 3 is 7.5 mm. 

 long. P 4 is 7 mm. long. P 6 is 6.5 mm. long. P 8 is 6 mm. long. The distal pinnules 

 are 13 mm. long with 18-20 segments on which the crest of the prismatic ridge is finely 

 spinous. 



The disk, especially along the ambulacra! grooves, is thickly beset with small 

 rounded plates, which become produced along the ambulacra. 



Notes. — The specimen from the Danish Expedition to the Kei Islands station 12 

 has about 40 arms (of which 25 are present) 150 mm. long; one postradial series is broken 

 off at the distal end of the IBr 2 , another at the IIBr,. Of the IIBr series five are 4(3+4) 

 and two are 2; three are missing. Of the IIIBr series six are 2 and three are 4(3+4). 

 There are two IVBr series, both next the midradial line but on different postradial series. 



The specimen from the Danish Expedition to the Kei Islands station 56 is small with 

 18 arms about 80 mm. long; the cirri have 39-13 segments and are 24-32 mm. long. 



The specimen from the Danish Expedition to the Kei Islands station 58 is a mag- 

 nificent example of the species with 24 arms 170 mm. long. Ten IIBr 4(3+4) series 

 are present. There are four IIIBr series, two on each of two postradial series. On each 

 ray one is internal and the other, on the other IIBr series, is external. The cirri are 

 XXXIV, 72-76, from 70 to 75 mm. long. 



The specimen from south of western Timor has 21 arms 175 mm. long. Of the ten 

 IIBr series present eight are 4(3+4) and two are 2, both the latter being on the same 

 IBr series. There is a single IIIBr 4(3+4) series, which is developed on the outer side 

 of one of the two IIBr 2 series. The cirri have 63-65 segments and are up to 60 mm. in 

 length. The dorsal pole of the centrodorsal is strongly convex and rugose. 



This specimen differs from the type only in minor details. The type specimen, 

 which is much broken, was said to have an arm length of about 120 mm. This estimate 



