A MONOGRAPH OF THE EXISTING CRINOIDS 535 



of the basal rays an equilateral triangle with convex sides and the apex reaching 

 almost or quite to the IBr axillary. The IBr: are short and very broad with the 

 lateral borders concave, corresponding to the convex sides of the interradial triangles 

 formed by the anterolateral angles of the radials, over the apices of which they meet 

 in more or less blunted points. The IBr2 (axillarics) are almost or quite triangular, 

 from three to three and one-half times as broad as long, and arc almost or quite in 

 lateral contact. The lIBr series are 4 (3 + 4), strongly rounded dorsally, and sepa- 

 rated interiorly by the very stout basal portion of the Pd, wliich are just in contact. 

 The IIIBr series, IVBr series, and VBr series are all 4 (3 + 4), the last usually present 

 in about half of the full number, the others all present. The division series are all 

 strongly rounded dorsally and are separated by the broad basal portions of the 

 pinnules which they bear, these being always just in contact, so that no perisome is 

 visible in a dorsal view. 



The arms are 48-120 in number, usually about 80, and are from 140 to 205 

 mm. in length. They are rather strongly compressed laterally and rather strongly 

 rounded dorsally. The first brachials are wedge-shaped, about twice as broad as 

 the interior (lesser) length, and almost entirely or quite united interiorly. The 

 second brachials are oblong, about t\vice as broad as long. The first syzygial pair 

 (composed of brachials 3 + 4) is about as long as broad. The following 5 brachials 

 are oblong, about twice as broad as long, and those succeeding become wedge- 

 shaped and after the thirteenth almost or quite triangidar, about twice as broad as 

 long, and after the ends of the proximal third of the arm gradually shorter, the ends 

 at the same time becoming less and less oblique, so that the brachials in the outer 

 half of the arm are almost or quite oblong and four times as broad as long, or even 

 rather broader. The dorsal and lateral surfaces of the elements of the division 

 series are slightly concave, causing the ends of the ossicles to appear rather promi- 

 nent, and the brachials after the eighth or tenth develop strongly produced and 

 overlapping distal ends which are armed with fine spines. 



Syzygics occur between bracliials 3 + 4, again from between brachials 10 + 11 to 

 between brachials 38 + 39 (usually with a variation of from 4 to 6 brachials in any 

 one individual), and distally at intervals of from 3 to 10 (usually 4) muscular articu- 

 lations. In the specimen from the Pelew Islands the second syzygy varies from 

 between brachials 26 + 27 to 30 + 31, and the distal intersyzygial interval is almost 

 invariably 4 muscular articulations. 



The disk is from 30 to 45 mm. in diameter. The mouth is radial or interra- 

 dial, usuall.v intermediate between these two positions, marginal or submarginal. 

 The anal tube is subcentral. The disk is naked, or bears a few scattered calcareous 

 granules, most commonly in the anal area. 



Pd is very long, from 30 to nearlv 60 mm. in length, according to the size of the 

 specimen, very stout basally, 2 mm. broad at the base in a large example, but evenly 

 tapering and becoming comparative)}' slender after the middle. It is composed of 

 70-75 segments all of which are about half again as broad as long except those 

 in the terminal portion, which are about as long as broad. The terminal comb con- 

 sists of 17 teeth which are low, roughly transversely oval, becoming more nearly 

 circular distally, with a strongly constricted pedicel, and not so high as the width 



