290 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Locality. Zanzibar; M. Kousseau, 1841 [A. H. Clark, 1911, 1912, 1918] (1, 

 P. M.). 



History. Dr. P. H. Carpenter examined this specimen in the Paris Museum, 

 placing with it a label indicating that it was an undescribed form differing from 

 H. joubini (see p. 312). It was described in 1911 both in a paper on the recent 

 crinoids in the Paris Museum and in a memoir on the crinoids of the coasts of Africa. 



HETEROMETRA SINGULARIS A. H. Clark 



PLATE 36, FIGURES 161-163 

 [See also vol. 1, pt. 2, fig. 269 (arm and pinnules), p. 207; figs. 455, 456 (pinnule tip), p. 261.] 



Heterometra singularis A. H. CLARK, Proc. U. S. Nat. Mus., vol. 36, 1909, p. 638 (description; south- 

 ern portion of Malacca Strait) ; Vid. Medd. Nat. Foren. K0benhavn, 1909, p. 164 (Singapore; 

 description of a specimen), p. 193 (collected at Singapore by Svend Gad); Crinoids of the 

 Indian Ocean, 1912, p. 128 (synonymy; detailed description; localities), fig. 11, p. 129; Unstalked 

 crinoids of the iSibogo-Exped., 1918, p. 78 (in key; range); Journ. Linn. Soc. (Zool.), vol. 36, 

 1929, p. 638 (80 miles northwest of Penang; notes); Rec. Indian Mus., vol. 34, pt. 4, 1932, 

 p. 551 (listed), p. 556 (Investigator station 548, 549; notes). GISLN, Kungl. Fysiogr. Sallsk. 

 Handl., new ser., vol. 45, No. 11, 1934, p. 22. 



Diagnostic features The brachials are distinctly wedge-shaped with the ends 

 never quite parallel and are not exceedingly short. The enlarged lower pinnules are 

 smooth, with the earlier segments keeled. The cirri are about 35 mm. long with 

 36-39 segments of which the longest are about as long as broad and the outer are 

 slightly broader than long and bear conspicuous dorsal spines. The 12-20 arms are 

 90-150 mm. long. P 2 is the largest pinnule, P 3 being of the same length as PI. 



Description. The centrodorsal is discoidal, the bare polar area flat, 1.5 mm. in 

 diameter. The cirrus sockets are arranged in a single crowded, more or less irregular, 

 marginal row. 



The cirri are XVII, 21-25, 12 mm. long. The first segment is short, the second 

 is about twice as broad as long, the third is somewhat longer, and the fourth is about 

 as long as broad. The next two are slightly longer than broad, and those following 

 gradually decrease in length so that the terminal 15 are one-third to one-half again 

 as broad as long. On the seventh subterminal dorsal spines begin to develop and 

 soon become long and prominent. The opposing spine is large and long, much larger 

 than the spines on the preceding segments, triangular, the apex terminal, arising from 

 the whole surface of the penultimate segment and about equal to the width of that 

 segment in height. The terminal claw is nearly twice as long as the penultimate seg- 

 ment, slender, abruptly curved proximally, becoming nearly straight distally. 



The radials are short, oblong, the dorsal surface with numerous prominent 

 rounded tubercles. The IB^ are short, oblong, slightly over four times as broad as 

 long, in close lateral apposition. The IBr 2 (axillaries) are broadly pentagonal, almost 

 triangular, twice as broad as long, the lateral edges shorter than those of the IBr,. 

 The IIBr are 4(3+4); the ossicles up to and including the second brachial exteriorly 

 and the fourth interiorly, as well as the first two segments of the first three pinnules, 

 are in close apposition and sharply flattened, the lateral edges somewhat produced. 



The 11 arms are 40 mm. long. The first two brachials are subequal, wedge- 

 shaped, about twice as broad as the exterior length, the first interiorly united. The 

 first syzygial pair (composed of brachials 3+4) is slightly longer interiorly than 



