A MONOGRAPH OF THE EXISTING CRINOIDS 579 



described a second specimen that I had found in the collection labeled Antedon Ivarii- 

 spina. 



In my memoir on the unstalked crinoids of the Siboga expedition published in 

 1918, I recorded and gave notes on a specimen of Mariametra vicaria from station 49a. 

 In the key to the species of Mariametra I included vicaria, with a footnote giving 

 M. margaritifera A. H. Clark as a synonym. 



MARIAMETRA DELICATISSIMA (A. H. Clark) 



Plate 61, Figures 279, 280 

 [See also vol. 1, pt. 1, fig. 17 (disk), p. 67.] 



Antedon delicatissima A. H. Clark, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 131 (color), p. 149 

 (description; Albatross station 4930). 



Himerometra delicatissima A. H. Clark, Smithsonian Misc. Coll., vol. 50, 1907, p. 356 (listed); 

 Proc. U. S. Nat. Mus., vol. 34, 1908, p. 317 (Japan). 



Dichrometra delicatissi7na A. H. Clark, Crinoids of the Indian Ocean, 1912, p. 149 (synonymy; 

 locality). 



Mariametra delicatissima A. H. Clark, Ann. Mag. Nat. Hist., ser. 8, vol. 10, 1912, p. 33 (compared 

 with M. tuberadata) ; Proc. Biol. Soc. Washington, vol. 26, 1913, p. 144 (listed); Journ. Wash- 

 ington Acad. Sci., vol. 5, 1915, p. 214 (southern Japanese species; range and its significance); 

 Unstalked crinoids of the Siboga Exped., 1918, p. 108 (in key: range). — Gislen, Kungl. Fysiogr. 

 Sallsk. Handl., new ser., vol 45, No. 11, 1934, p. 25. 



Diagnostic features.- — The arms are about 30 in number, 70 mm. long; beyond the 

 second brachial they bear a narrow interrupted dark stripe that extends nearly their 

 entire length; the cirri, which are nearly half as long as the arms, have 40 segments 

 of which the longest earlier are much elongated and the distal are simply carinate 

 dorsally; P 3 is much the longest pinnule, 11 mm. long with about 20 elongated cylin- 

 drical segments. 



Descrifiion. — The centrodorsal is low hemispherical, with a large bare polar 

 area. The cirri are marginal. 



The cirri are about XXX, 40, 30 mm. long. The earlier segments are much 

 elongated and the distal are short; none of them bear dorsal spines. 



The radials are concealed. The IBr, are short and are in lateral contact in the 

 basal half. The IBr 2 (axillaries) are low pentagonal and are well separated laterally. 

 The IIBr and IIIBr series are 2, the latter being developed only externally. They 

 resemble the IBr series but are proportionately longer. The lateral ornamentation 

 of the division series is reduced to a slight and very inconspicuous roughening of 

 the sides of the ossicles, the dorsal surface being entirely smooth. 



The 28 arms are 70 mm. long. The first 10 brachials are oblong, and those 

 following are short wedge-shaped, becoming oblong again distally. 



Syzygies occur between brachials 3+4 (sometimes between brachials 2+3), 

 again from between brachials 15 + 16 to between brachials 21+22, and distally at 

 intervals of from 4 to 6 muscular articulations. 



P, is short, 5 mm. in length, and is composed of 15 short segments. P 2 is longer 

 than Pj. P 3 is much the longest pinnule, 11 mm. long, with about 20 elongated 

 cylindrical segments. The pinnules following are short, becoming longer again and 

 slender distally. 



