A MONOGRAPH OF THE EXISTING CRINOIDS 171 



The arms are 10-12 (usually 10) in number, 1 10 mm. in length. The first 6 brachials 

 are oblong, broader than long, and those following are triangular, about as long as broad, 

 becoming wedge-shaped and longer distally. The triangular lower brachials have 

 projecting distal edges which increase in prominence distally, becoming in the distal 

 third of the arm long curved overlapping spines. 



Syzygies occur between brachials 3 + 4, again at about brachials 21 + 22, and 

 distally at intervals of from 3 to 5 muscular articulations. Following a IIBr series 

 brachials 1 + 2 are united by syzygy. 



P! is 6 mm. long, very stout basally but tapering rapidly after the seventh or 

 eighth segment, strongly prismatic, sharply flattened exteriorly, and often more or less 

 carinate. It is composed of about 12 segments which are very short basally, but become 

 longer than broad terminally. P 2 and the following pinnules are shorter and much more 

 slender, and are composed of fewer segments, which are somewhat longer than broad. 

 The distal pinnules are about 10 mm. long, slender, the first 2 segments expanded and 

 trapezoidal, the remainder about twice as long as broad, becoming more elongate 

 distally. 



The color in alcohol is white, with the division series and the first 2 brachials 

 dark brown. 



Localities. — Albatross station 3475; off Oahu, Hawaiian Islands (lat. 21°08'00" 

 N., long. 157°43'00" W.); 642 meters; fine white sand; December 6, 1891 [A. H. Clark, 

 1907, 1908, 1909, 1912, 1915, 1918] (3, U.S.N.M., 22653, 35586) 



Albatross station 3476; off Oahu, Hawaiian Islands (lat. 21'09'00" N., long. 

 157°53'00" W.); 545 meters; fine white sand; December 6, 1891 [A. H. Clark, 1908, 

 1909, 1912, 1915, 1918] (1, U.S.N.M., 35585). 



History. — This species is as yet known only from the four specimens collected by 

 the Albatross in 1891. 



THALASSOMETRA LATIPINNA (P. H. Carpenter) 



Antedon latipinna P. H. Carpenter, Challenger Reports, Zoology, vol. 26, pt. 60, 1888, p. 116 (descrip- 

 tion; Challenger station 232), pi. 10, fig. 3.— Hartlaub, Bull. Mus. Comp. Zool., vol. 27, No. 4, 

 1895, p. 131 (systematic and bathymetrical relationships). — A. H. Clark, Proc. U. S. Nat. Mus., 

 vol. 33, 1907, p. 129 (comparison, in key, with A. pubescens). — Hamann, Bronn's Klassen und 

 Ordnungen des Tier-Reichs, vol. 2, Abt. 3, 1907, p. 1578 (listed).— A. H. Clark, Proc. Biol. Soc. 

 Washington, vol. 22, 1909, p. 18 (not placed iu a revision of the Thlassometridae) ; Crinoids of the 

 Indian Ocean, 1912, p. 33 (of P. H. Carpenter, 1888= Thalassometra latipinna). 



Thalassometra latipinna A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 360 (listed); 

 Proc. U. S. Nat. Mus., vol. 34, 1908, p. 318 (Japan); Crinoids of the Indian Ocean, 1912, p. 208 

 (synonymy; locality); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 46 (published reference 

 to specimen in the B. M.; Challenger station 232; characters of the division series and lower 

 brachials); Journ. Washington Acad. Sci., vol. 5, No. 6, 1915, p. 215 (southern Japanese species; 

 range and its significance); Unstalked crinoids of the Siboga-Exped., 1918, p. 167 (in key; range), 

 p. 170 (references). 

 Diagnostic Jeatures. — The elements of the division series and first two brachials 



have the edges finely spinous; the distal edges of the brachials are not produced; and 



the cirri are arranged in 10 definite columns on the centrodorsal. The 10 arms are 40 



mm. long, and the cirri are 30 mm. long with 40 segments. 



Description. — The centrodorsal is truncated conical, about 3 mm. broad at the base, 



1.7 mm. across the flat dorsal pole, and 3 mm. high. The cirrus sockets are arranged 



in 10 apparently evenly spaced columns of 2 each. 



