A MONOGRAPH OF THE EXISTING CRINOIDS 205 



are about XX, about 25, about 18 mm. long, and stout. The distal border of the 

 segments is somewhat produced. The distal segments bear small spines, and the 

 antepenultimate carries a stout opposing spine. The radials are partially visible later- 

 ally. The IBr, are entirely free laterally. The IBr 2 (axillaries) are pentagonal. The 

 IIBr series are 4(3+4), and the IIIBr series are 2. The two ossicles following the 

 IBr axillaries are partially united interiorly. The. articulations are smooth. The 

 IBr axillaries and immediately following ossicles have no lateral processes. The arms 

 are apparently not more than 30 in number and are all broken. The brachials are 

 short and overlapping with, except for the first two, strongly produced distal ends. 

 The first syzygy is between brachials 3+4, and the next is about the twenty-fourth 

 brachial. P D is very stout and stiff, about 9 mm. in length, with 12-15 segments, of 

 which the three basal are very large and those following decrease abruptly in size. 

 Pi is smaller and less stiff, although its basal segments are also very large. P 2 is much 

 smaller, scarcely 4 mm. long, and beyond the basal segments rapidly becomes slender. 

 The disk is 10 mm. in diameter, and is deeply incised. Sacculi are rather sparsely 

 distributed on the pinnules. The color of the skeleton is gray-brown. 



Hartlaub remarked that this specimen is unfortunately much broken. As shown 

 in his figure the amis are all broken away at the articulation between the first and 

 second brachials except for a single stump including 15 brachials. But, as Hartlaub 

 says, the characters by which the species represented differs from other species are 

 well shown. Especially characteristic are the massive lower pinnules, quite unique in 

 form, and the strongly produced distal ends of the fourth and following brachials. He 

 said that this species is nearest Antedon kraepelini {=Himerometra robustipinna) from 

 Akyab with which, as also with others, it agrees in the position of the second brachial 



syzygy- 



As it is shown on the plate Hartlaub's figure of P D (pi. 1, fig. 6) is deceptive, for 

 the shading gives the impression that the pinnule and the portion of the arm shown 

 are sharply flattened laterally more or less like Pi and the adjacent portion of the arm 

 base in a species of Thalassometra. But if the figure is viewed upside down it gives 

 the proper impression of convexity. 



I have examined the type specimen of Hartlaub's Antedon martensi. It is a 

 rather small and badly broken specimen, but it agrees in every particular with the 

 specimens in the Copenhagen Museum, with which it was compared directly. 



Some of the specimens collected by Svend Gad at Singapore present the follow- 

 ing characters: 



June 15, 1905; one has 31 arms 70 mm. long, and the other has 36 arms 70 mm. 

 long. 



June 16, 1907; the five specimens have 29-43 arms 65-80 mm. long. 



November 27, 1907; three specimens with 27 arms 70 mm. long, 37 arms 80 mm. 

 long, and 38 arms 70 mm. long. These specimens are typical of the whole series. 

 The centrodorsal has a broad, slightly concave, dorsal pole. The longest cirri have 

 about 30 segments, sometimes rather less, but more commonly rather more. The 

 IIBr series are always present, and are almost invariably 4(3+4). The exterior 

 IIIBr series are 4(3 + 4) and the interior are 2; when a deficiency in the IIIBr series 

 occurs the exterior IIIBr series are usually lacking, so that there is a tendency toward 

 a IIIBr arrangement of 1, 2, 2, 1. The IVBr series, when present, are 2, and are 



