A MONOGRAPH OF THE EXISTING CRINOIDS 205 



Bronn's Klassen und Ordnungen des Tier-Reichs, vol. 2, Abt. 3, 1907, p. 1578 (listed). — A. H. 



Clark, Crinoids of the Indian Ocean, 1912, p. 33 (identity). 

 Charitometra aculeata A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 361 (listed). — 



Geogr. Journ., vol. 32, No. 6, 1908, p. 603 (type of a nonoceanic group of the genus). 

 Chlorometra aculeata A. H. Clark, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 22 (listed); Proc. 



U. S. Nat. Mus., vol. 39, 1911, p. 558 (compared with Ch. robusta) ; Crinoids of the Indian Ocean, 



1912, p. 33 (identity), p. 225 (synonymy; locality); Smithsonian Misc. Coll., vol. 61, No. 15, 



1913, p. 49 (published reference to specimen in the B. M.; Challenger station 214; character of 

 the brachial carination). 



Chondrometra aculeata A. H. Clark, Journ. Washington Acad. Sci., vol. 6, No. 17, 1916, p. 608 (listed) ; 

 Unstalked crinoids of the Siboga-JZxped., 1918, p. 188 (in key; range). 



Diagnostic features. — The centrodorsal is conical, much broader at the base than 

 high, with the cirrus sockets arranged in 5 more or less regular midradial columns; the 

 arms are 75 mm. long; and the cirri are 27 mm. long with about 18 segments. 



Description. — The centrodorsal is subconical, rather small, with the cirrus sockets 

 in 5 somewhat irregular midradial columns of 2, 3, or occasionally 4, all the columns 

 converging at the apex of the centrodorsal. 



The cirri are about XV, about 18; most of the segments are longer than broad. In 

 the figure the first segment is very short, the second is rather more than twice as broad 

 as long, the third is about twice as broad as long, and those following are from one-third 

 to one-half again as long as broad. The penultimate segments bear an inconspicuous 

 opposing spine. The figure shows a cirrus almost straight and tapering slightly in the 

 distal half; the terminal claw is shown as only slightly curved. 



The radials are short and bandlike, marked by occasional grooves and projections. 

 The IBr t are longer, with flattened lateral borders, but sharply convex in the center 

 where they rise to meet the posterior projection of the axillaries. The IBr a (axillaries) 

 and the first four brachials have a high center and depressed margin like the IBri, with 

 sharp lateral edges and flattened sides. 



The 10 arms are probably about 75 mm. long. The proximal brachials are rather 

 short with a sharp mediodorsal line, those following wedge-shaped and more distinctly 

 carinate so as to overlap. The figure shows the brachials rather sharply carinate with 

 the dorsal profile rising from the proximal to the distal end so that the profile of the 

 arm as a whole is strongly serrate. 



Syzygies occur between brachials 3+4, again between about brachials 15+16, 

 and distally at intervals of from 6 to 9 oblique muscular articulations. 



Pi is rather larger than its successors, the basal segments of which are short and 

 laterally compressed with a sharp dorsal edge. In the pinnules of the eleventh and 

 following brachials the third segment and its successors are not expanded but gradually 

 become longer than broad, and in the terminal third much elongated. Carpenter said 

 that insofar as he was able to make out without mutilating the specimen the proximal 

 pinnules have somewhat the trdiedral form with flattened outer sides that is charac- 

 teristic of Charitometra basicurva. Their next successors are altogether different, 

 however, the third and following segments becoming relatively longer until they 

 attain the usual elongated shape which is characteristic of the middle and distal pinnules. 

 But they acquire this shape at about the eleventh or thirteenth brachial so that they 

 differ from the broad and expanded pinnules in the corresponding part of the arms of 

 Glyptometra tuberosa. 



