21g BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



vol. 7, No. 1, 1936, p. 4 (Macclesfield Bank), p. 5 (range).— A. H. Clark, John Murray Exped. 



1933-34 Sci. Reports, vol. 4, No. 4, 1936, p. 104. — H. L. Clark, Echinoderm fauna of Australia, 



1946, p. 49 (Australian locality). 

 Oligometra pulchella A. H. Clark, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 226 (description; 



Singapore) ; Smithsonian Misc. Coll., vol. 52, pt. 2, 1908, p. 222 {Albatross station 5139); Proc. 



Biol. Soc. Washington, vol. 22, 1909, p. 7 (listed), p. 42 (compared with O. [Decametra] studeri); 



Proc. U. S. Nat. Mus., vol. 36, 1909, p. 399 {Albatross station 5248); Vid. Medd. Naturh. Foren. 



K0benhavn, 1909, p. 180 (synonym of serripinna) ; Unstalked crinoids of the Siboga-'Exped., 



1918, p. 129, footnote (=0. serripinna). 

 Oligometra occidenlalis (part) A. H. Clark, Proc. U. S. Nat. Mus., vol. 43, 1912, p. 382 (Bagamoyo); 



Unstalked crinoids of the Siboga-Exped., 1918, p. 129 (southeastern Africa). 

 Oligometra serripinna occidenlalis (part) A. H. Clark, Proc. U. S. Nat. Mus., vol. 43, 1912, p. 401 



(Bagamoyo).— Hartmeter, Mitt. Zool. Mus. Berlin, vol. 8, No. 2, 1916, p. 236 (specimen from 



Bagamoyo in U. S. N. M.). 

 Oligometra concinna A. H. Clark, Crinoids of the Indian Ocean, 1912, p. 172 (Puri; detailed descrip- 

 tion as a form of serripinna); Unstalked crinoids of the Siboga-Exped., 1918, p. 129, footnote 



( = 0. serripinna). 

 Oligometra carpenteri (part) H. L. Clark, The echinoderm fauna of Torres Strait, 1921, p. 24 (Mer- 



ton's specimens from Little Kei I.). 

 Oligometra serripinna serripinna A. H. Clark, John Murray Exped. 1933-34, Sci. Reports, vol. 4, 



No. 4, 1936, p. 101 (range). 



Diagnostic features. — Pa is stiffened and enlarged, though not exceptionally stout, 

 straight or with the outer portion ciu-ved away from the disk, composed of segments 

 which are mostly, or largely, longer than, or at least as long as, broad, with the distal 

 ends of the prismatic ridges more or less strongly produced or bearing one or more 

 spines, so that the profile of the pinnule as a whole is more or less strongly serrate. 



Description. — The centrodorsal is thin discoidal with the broad circular dorsal 

 pole, which is 2 mm. in diameter, flat, the border slightly raised at the base of each 

 cirrus. The cirrus sockets are arranged in a single regular marginal row. They are 

 much crowded so that they are about twice as high as broad with the lateral borders 

 straight and the upper and lower borders strongly arched. 



The cirri are XV, 20, 8-9 mm. long, short, rather stout, and strongly recurved. 

 The first segment is very short, the second is about four times as broad as long, and 

 those following gi-adually increase in length to the three or four terminal, which are 

 about twice as broad as the median length or slightly longer. The second segment has 

 the distal edge dorsally produced and serrate. On the segments following this be- 

 comes a prominent narrow transverse ridge with a straight crest situated near the 

 distal edge. Distally the ridge gradually moves proximally so that on the segments 

 in the outer thu'd of the cirri it is in the middle of the dorsal surface of the segments. 

 In the termmal fourth of the cirri it narrows so that on the antepenultimate segment 

 it is usually scarcely more than a laterally broadened tubercle. The opposing spine 

 is erect, conical, rather short, scarcely one-third the width of the penultimate segment 

 in height, and arises from only a portion of the dorsal surface. It is sometimes more 

 or less broadened laterally. Viewed dorsally the cirri are seen to be much compressed 

 at the base, the first segment being only about two-thirds as broad as the second, which 

 is usually slightly less broad than the third. Fi'om the third segment onward the cirri 

 remain of about the same width to the middle, then gradually narrow to the tip. 



The distal edges of the radials are even with the rim of the centrodorsal, or extend 

 very slightly beyond it. They are produced upward, somewhat abruptly, in the inter- 



