A MONOGRAPH OF THE EXISTING CRINOIDS 195 



of Carpenter's robustipinna) . — Reichenspbrgee, Abh. Senck. naturf. Ges., vol. 35, Heft 1, 

 1913, p. 97 (synonym of kraepelini), p. 98 (further discussion). 

 Himerometra inopinata A. H. Clark, Crinoids of the Indian Ocean, 1912, p. 114 (type of Antedon 

 inopinata Bell, 1894, redescribed and shown to be a Himerometra; correction of the original depth 

 record) . 



Diagnostic features. — The enlarged proximal pinnules are very stout and taper 

 rapidly to the tip; they are composed of 17-24 (but almost always 20) segments of 

 which the distal ends may be unmodified or swollen, but are never spinous; the distal 

 edges of the proximal brachials are smooth, or only slightly produced. There are 

 37-56 (usually about 45) arms, which are 100-200 (usually 130-140) mm. long. 



Description.- — The centrodorsal is as in the other species of the genus. 



The cirri are XXX, 26-34, stout, 30-35 mm. long. The sixth or seventh seg- 

 ments are the longest, from slightly broader than long to half again as broad as long. 

 The distal segments are slightly carinate, the carination on the last six or seven ending 

 distally in a small spine. 



Nine of the IIBr series are 4 (3+4) and two are 2; the IIIBr series are all 4 (3+4) 

 except one, internally developed; the remaining division series are all 4 (3+4) except 

 two IVBr series, which are 2. The division series are strongly convex and well sepa- 

 rated as is usual in the genus. 



The 46 arms are 140 mm. long and resemble those of the other species of the genus. 



The proximal pinnules are very stout but nearly smooth, the distal edges of the 

 segments being only very slightly swollen. All the segments are short, about twice as 

 broad as long in the proximal half, becoming squarish toward the tip. The proximal 

 pinnules are about 20 mm. long, with 17-20 segments. 



Notes. — The specimen from Albatross station 5165, which was described as the 

 type of a new species Himerometra robustipinna, has 37 arms 100 mm. long. The 

 cirri are XVIII, 30-40, 35 mm. long; they are without dorsal spines, though the last 

 three segments may have small median tubercles. The proximal pinnules are very 

 stout, with most of the segments, which number about 20, broader than long and 

 smooth. P D is 15 mm. long. 



In the type specimen of Antedon inopinata from the Macclesfield Bank, according 

 to Bell, the centrodorsal is large, hollowed in the center, which is bare of cirrus pits; 

 the cirri are arranged in three irregular rows on the side. The cirri are long and stout, 

 about XLV, about 40, up to 28 mm. in length; the terminal segments are faintly 

 spinous. The radials and the IBri are broad and stout, and the IBr 2 (axillaries) are 

 short at the side. The IIBr series are 4 (3+4). There are nearly always IIIBr 

 4 (3+4) series present. In rare cases there may be IVBr 2 series. The arms are 

 about 45 in number, and are about 100 mm. long. The brachials are wide, low, and 

 very regular and are much compressed laterally. Syzygies occur between brachials 

 3+4, then not again for about 26 muscular articulations. The pinnules generally are 

 pretty stout and stiff, the basal ones being very markedly stout. The color in alcohol 

 is light brown, with the ambulacral surface of the pinnules somewhat darker. 



Dr. P. H. Carpenter described Actinometra robustipinna as follows: The centro- 

 dorsal is a thick disk slightly flattened at the dorsal pole and bearing about 40 cirrus 

 sockets in 2 marginal rows. The radials are partially visible all around the calyx, 

 but they diverge slightly at each angle so as to leave a gap. This is bridged over by 



