178 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



(that is, of Oligometra serripinna) collected by Prof. Sir William Herdman off the coast 

 of Ceylon the ridge is near the distal end in the first few segments, and becomes median 

 in the later ones. On the last few segments it is represented by a pair of parallel 

 spines, and the penultimate segment bears a strong opposing spine. In relative size 

 the proximal pinnules resemble those of the specimens from Ceylon, but the number 

 of pinnule segments is larger. The second syzygy is between brachials 10+11 or 

 11 + 12, and the third is between brachials 16+17. 



In a review of Mr. Chadwick's paper on the crinoids of the Sudanese Red Sea 

 published in April 1909, 1 remarked that the specimens recorded as Antedon serripinna 

 differ from the type of Oligometra serripinna in the greater number of cirrus segments 

 and, in view of the general constancy of the cirrus characters in this genus, may 

 eventually turn out to be a recognizable form, as may also those recorded under the 

 same name from Ceylon ; correlated, as usual, with the more numerous cirrus segments, 

 the lower pinnules also have more numerous segments. In my paper on the crinoids 

 of the Copenhagen Museum published later in 1909 I mentioned that Oligometra serri- 

 pinna had been recorded from the Red Sea. 



Thanks to the kindness of Prof. Sir William Herdman the United States National 

 Museum secured one of the specimens upon which Chadwick's record was based. In 

 1911 hi a paper on the crinoids of the coasts of Africa this specimen was described by 

 me as the type of a new species which I called \Colobometra chadwicki. In my 

 memoir on the crinoids of the Indian Ocean published in 1912 I listed Colobometra 

 chadwicki and gave the synonymy and range. In the appendix to this memoir this 

 species, under the name C\olobometra]. (P[rometra] .) chadwicki, was compared with the 

 new species Colobometra (Prometra) brevicirra. 



In 1913 Prof. Charles L. Boulenger described the myzostomes from Chadwick's 

 specimens, which he recorded as Antedon serripinna. 



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

 1918 chadwicki was included in the key to the species of Prometra and the range was 

 given. 



DECAMETRA TIGRINA (A. H. Clark) 



PLATE 19, FIGURE 98; PLATE 22, FIGURE J12; PLATE 24, FIGURES 123, 124; PLATE 26, FIGURE 133 



Antedon tigrina A. H. CLARK, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 147 (description; ?Kagoshima 

 Bay, Japan), p. 148, footnote (Sagami Bay; correctness of original locality established); Proc. 

 U. S. Nat. Mus., vol. 34, 1908, p. 497 (listed). HARTLAUB, Mem. Mus. Comp. Zool., vol. 27, 

 No. 4, 1912, p. 280 (listed), pp. 380, 381 (?Kagoshima Bay; detailed description and discussion), 

 pi. 13, fig. 1. 



Cyllometra tigrina A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 357 (listed) ; Proc. 

 U. S. Nat. Mus., vol. 34, 1908, p. 318 (Japan) ; Proc. Biol. Soc. Washington, vol. 22, 1909, p. 6 

 (listed). 



Decametra tigrina A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 164 (synonymy; southern 

 Japan); Proc. Biol. Soc. Washington, vol. 26, 1913, p. 179 (range in east Asia); Smithsonian 

 Misc. Coll., vol. 61, No. 15, 1913, p. 34 (Toba Harbor, Japan; Japan); Journ. Washington 

 Acad. Sci., vol. 5, No. 6, 1915, p. 214 (southern Japanese species; range and its significance); 

 Unstalked crinoids of the Siboga-Exped., 1918, p. 117 (in key; range). 



Prometra perplexa GISLEN, Vid. Medd. Dansk Naturh. Foren., vol. 83, 1927, pp. 2, 27 (description; 

 Mortensen's station 10); p. 68; figs. 15-18, p. 27; fig. 82, pi. 1. 



Diagnostic features. The cirri are 10-13.5 mm. long with 18-26 (most commonly 

 20) segments of which the seventh or eighth and following are about as long as broad, 



