102 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



quite constant. It seems to be most nearly related to Oligometra japonica (Hart- 

 laub), but differences in the cirri, the number and arrangement of the syzygies, and in 

 the lower pinnules made him think it probably distinct, and until specimens can be 

 compared it is better to keep the two forms separate. He said a fine orange-brown 

 and white individual was notable for its very conspicuous lower pinnules and the stout 

 cirri. But he said that hi spite of individual diversities the species is really not very 

 variable in its essential specific characters. 



Upon the establishment of the new genus Iconometra by me in 1929, Iconometra 

 anisa was given as one of the three constituent species. 



ICONOMETRA MARGINATA (A. H. Clark) 



PLATE 10, FIGURES 50-52 



Oligometra marginata A. H. CLARK, Rec. Indian Mus., vol. 7, pt. 3, No. 26, 1912, p. 267 (nomen 

 nudum; a species related to 0. adeonae and 0. thetidis known from Solor Strait), p. 269 (cirri 

 compared with those of 0. [Decametra] intermedia); Ann. Mag. Nat. Hist., ser. 8, vol. 10, 1912, 

 p. 40 (description; Siboga station 305); Unstalked crinoids of the Siboga-Exped., 1918, p. 126 

 {Oligometrides adeonae [error]). GISLEN, Kungl. Svenska Vet. Handl., vol. 59, No. 4, 1919, 

 p. 33 (discussion). A. H. CLARK, Temminckia, vol. 1, 1936, p. 308 (identity). 



Oligometrides adeonae (part) A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. 126 

 (station 305; description), p. 276 (listed), pi. 20, fig. 49. 



Iconometra marginata A. H. CLARK, Temminckia, vol. 1, 1936, p. 295 (listed), p. 308 (Snellius station 

 60*; notes). 



Diagnostic features. -A small and delicate form with 10 arms 30 mm. long; P, is 

 slightly longer than P 2 , though slightly less stout; the proximal pinnules have 8 or 9 

 segments; the cirri are XV, 15-16, 7 mm. long. 



The three specimens referred to this species are all small and immature. They 

 may prove to be the young of /. anisa. 



Description.- The dorsal pole of the ceutrodorsal is papillose. 



The cirri are XV, 15-16, 7 mm. long, and are moderately stout. The first segment 

 is short, those following gradually increasing in length so that the fourth, fifth, or 

 sixth and following are about as long as broad. The third and following segments 

 have a strong transverse ridge near the proximal dorsal margin. This ridge is promi- 

 nent and high, with a finely serrate crest. It lies about one-third of the distance 

 between the proximal and distal margins of the segments. In the proximal half or 

 three-quarters of the cirri the distal dorsal edge of the segments is more or less everted, 

 so that there is the same bidentate appearance that is characteristic of the cirri of 

 0. adeonae. On the earlier segments this eversion of the distal edge may be nearly as 

 high as the transverse ridge, but it soon decreases in height and disappears entirely in 

 the distal half or quarter of the cirri. The smaller cirri are quite without it. 



The 10 arms are 30 mm. long. The proximal arm structure resembles that of 

 0. adeonae. The ossicles of the IBr series and the first two brachials are broad and are 

 in lateral contact through produced and flangelike ventrolateral borders the outer 

 edges of which are parallel to the longitudinal axes of the segments that bear them. 



Pj is 5 mm. long with 9 segments, rather slender but considerably stiffened, 

 recalling P 2 in the more delicate varieties of Stephanometra protectus. The first seg- 

 ment is about one-third again as broad as long, the second is half again as long as the 

 proximal width and is slightly trapezoidal, the third is about three tunes as long as its 

 proximal diameter, the fourth-sixth are slightly longer, and those following rapidly 



