A MONOGRAPH OF THE EXISTING CRINOIDS 165 



the ninth is a transition segment. The interradial pairs of columns of cirrus segments 

 are narrow and are widely separated by a broad midradial deeply concave bare area. 



Localities. Investigator; south of Kurrachi (lat. 2224'00" N., long. 6651'30" E.); 

 1,398 meters; bottom temperature 6.0 C.; green mud [A. H. Clark, 1909, 1911, 1912, 

 1913, 1918, 1937; Gislen, 1934] (6, U.S.N.M., 35591; I. M.). 



Mabahiss station 143; in the vicinity of the Maldive Islands (from lat. 515'48" N., 

 long. 7322'48" E. to lat. 513'42" N., long. 7323'36" E.); 797 meters; temperature 

 (at 770 meters) 7.88 C.; gray sand; March 30, 1934 [A. H. Clark, 1937] (1, B. M.). 



Off Mozambique (lat. 1648' S., long. 3940' E.); 914 meters; from a cable; cable 

 repair ship Lady Denison-Pender, Eastern and Associated Telegraph Co. [A. H. Clark, 

 1929] (1, B. M.). 



Geographical range. From off Kurrachi to the Maldive Islands and southwestward 

 to the coast of Mozambique. 



Bathymetrical range. From 797 to 1,398 meters. 



Thermal range. From 6.0 to about 7.88 C. 



History. Thalassometra attenuata was described in 1909 from 6 specimens dredged 

 off Kurrachi in 765 fathoms by the Royal Indian Marine Survey steamer Investigator. 

 In 1911 it was compared with the new species Th. hirsuta, and in 1912 in my memoir 

 on the crinoids of the Indian Ocean it was redescribed and figured. In 1913 I compared 

 it with the type series of Carpenter's Antedon gracilis. In my memoir on the un- 

 stalked crinoids of the Siboga expedition published in 1918 attenuata was included in 

 the key to the species of Thalassometra and the synonymy and range were given. In 

 1929 I recorded a specimen from off Mozambique in 500 fathoms that had been taken 

 from a cable brought to the surface by the cable repair ship Lady Denison-Pender of 

 the Eastern and Associated Telegraph Co. In 1934 Prof. Torsten Gislen discussed 

 certain features of the structure. In 1936 I recorded and gave notes on a specimen 

 from the John Murray Expedition to the Indian Ocean, 1933-34, that had been dredged 

 by His Egyptian Majesty's steamer Mabahiss at station 143 in the Maldive region in 

 797 meters. 



THALASSOMETRA HIRSUTA A. H. Clark 



PLATE 18, FIGURE 59 



Thalassometra hirsuta A. H. CLARK, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 552 (description; Alba- 

 tross station 5445; also stations 5275, 5474); Zool. Anz., vol. 39, No. 11/12, 1912, p. 426 (com- 

 pared with Th. margaritifera) ; Crinoids of the Indian Ocean, 1912, p. 206 (synonymy; range); 

 Unstalked crinoids of the Siboga-'Exped., 1918, p. 168 (in key; range), p. 169 (references; notes; 

 stations 85, 286), pp. 272, 275 (listed). GISLEN, Ark. Zool., vol. 19, No. 32, Feb. 20, 1928, 

 p. 7 (probably the same as Th. gracilis and Th. pubescent). 



Diagnostic features. The elements of the division series and lower brachials have 

 the edges all around strongly everted and coarsely spinous, with a coarsely spinous 

 median carination and a few coarse spines scattered over the dorsal surface; and the 

 cirri are arranged in 10 definite columns on the centrodorsal. There are 10 arms, 

 and the cirri are 30-45 mm. long with 48-66 (usually 54-66) segments. 



Description. The centrodorsal is low-conical, with the dorsal pole finely papillose. 

 The cirrus sockets are arranged in 10 columns of two or three each, the two columns in 

 each radial area being slightly separated proximally by a narrowly linear or wedge- 

 shaped papillose area. 



The cirri are slender, XV-XXV, 48-66 (usually 54-66), from 30 to 50 mm. long. 

 The first segment is short, those following increasing in length and becoming about as 



