A MONOGRAPH OF THE EXISTING CRINOIDS 15 



The color in alcohol is yellowish brown or whitish brown, with the perisome darker. 



The preceding description is adapted from the original description of Carpenter. 

 In the British Museum I examined three of the Challenger specimens, two large ones 

 and one small. The cirri are proportionately larger and stouter than those of the 

 Japanese 8. diadema. The arms are 100 mm. long. The sides of the division series 

 are denticulate. The lateral portions of the proximal borders of the ossicles of the 

 division series are also more or less denticulate. The crest of the carination is sharp, 

 and nearly or quite straight; there is no pronounced denticulation. 



Notes. Three of the specimens from Menado Bay, Celebes, have the cirri 50 mm. 

 long with 76-79, 74-75, and 75 segments. All the 18 specimens have apparently 20 

 arms. 



Of the three specimens from Rotti Strait one has 19 and another 21 arms, all the 

 division series being 2. The third specimen is curious in having eight of the nine 

 IIBr series 4, in two synarthrial pairs, instead of the usual 2. It was described as a 

 new species under the name of Stenometra diplax in the following terms: The centro- 

 dorsal is thick discoidal, about twice as broad at the base as high, 3 mm. in diameter 

 basally. The very broad dorsal pole is studded with evenly distributed rather short 

 and pointed papillae. The cirrus sockets are arranged in ten regular columns of two 

 sockets each, there being two columns in each radial area. In the interradial lines the 

 adjacent columns of cirrus sockets are separated by rather high ridges, in the midradial 

 lines by narrower, lower, and sharper ridges. 



The cirri are XX, 73-76, from 40 to 50 mm. long, very slender and delicate. The 

 first segment is exceedingly short, and those following gradually increase in length to the 

 fifth, which is half again as broad as long, the sixth, which is slightly longer than broad, 

 and the seventh-twelfth, which are the longest, about one-third again as long as broad. 

 Beyond the twelfth the segments very slowly decrease in length, so that those in the 

 terminal third of the cirri are about twice as broad as long. Beginning somewhat before 

 the middle of the cirri the distal ends of the segments become slightly produced dorsally. 

 This production of the distal edge gradually narrows and at the same time extends 

 proximally so that the short distal segments bear a prominent sharp median dorsal 

 carination, the crest of which in profile at first rises gradually from the proximal to the 

 distal end of the segment, but later becomes strongly convex. The opposing spine is 

 conical, blunt, slightly higher than the process on the segment preceding. The terminal 

 claw is scarcely as long as the penultimate segment, and is stout and strongly curved. 

 The proximal segments are carinate ventrally, and the ventral and lateral portions of 

 the distal edge are produced, overlapping the bases of the segments succeeding. Tin's 

 feature gradually dies away as the segments become shorter. In lateral view the cirri 

 taper very slightly in the basal fourth and then remain of uniform width until near the 

 end, when they taper gradually to the tip. 



The ends of the basal rays are visible as minute tubercles at the upper ends of the 

 interradial ridges on the centrodorsal. 



The radials are extremely short, chevron-shaped, with the distal border narrowly 

 and the lateral edges thickly everted and irregularly dentate. The IBn are chevron- 

 shaped, very narrow and bandlike, from six to eight times as broad as long. The proxi- 

 mal edge bears a few scattered teeth or lobes or other irregularities, and the lateral 

 portions of the distal edge are more or less strongly dentate. The IBr 2 (axillaries) are 



