728 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



sokotrae than in the species of Fariometra, the difference is less than that between 

 sokotrae and the species of Thaumatometra. There seem to me to be no characters of 

 much significance distinguishing between the two genera other than those furnished 

 by the cirri. 



Locality. Northwest of Sokotra, Arabian Sea (lat. 1420' N., long. 5230' E.); 

 2194 meters; cable repair ship Electra; July 10, 1909 [A. H. Clark, 1911, 1912, 1913, 

 1915, 1937; John, 1937] (5, B.M.). 



History. During a visit to the British Museum in 1910 I examined the five speci- 

 mens upon which this species is based, but did not have time to draw up a description 

 of them. I mentioned them as Thaumatometra, sp. in several papers, including the 

 report of the John Murray Expedition in 1937, which prompted Dr. Dilwyn John to 

 describe and name the species later in the same year. 



FARIOMETRA EXPLICATA (A. H. Clark) 



[See vol. 1, pt. 1, fig. 224, p. 243] 



Trichometra explicate, A. H. CLARK, Smithsonian Misc. Coll., vol. 52, pt. 2, 1908, p. 232 (description; 



Albatross sta. 5123); Proc. U.S. Nat. Mus., vol. 39, 1911, p. 563 (Albatross sta. 5349); Crinoids 



of the Indian Ocean, 1912, p. 239 (synonymy; Philippine Is., 283-730 fms.). 

 Fariometra explicate A. H. CLARK, Journ. Washington Acad. Sci., vol. 7, No. 5, 1917, p. 130 (listed); 



Unstalked crinoids of the Siboga-Exped., 1918, p. 249 (in key; range), p. 250 (synonymy; 



Albatross stas. 5123, 5115, 5349). 



Diagnostic features. The ossicles of the division series and the first two brachials 

 are in close lateral contact throughout and sharply and broadly flattened laterally; the 

 cirri have up to 28 segments. 



Description. The centrodorsal is conical, in lateral view an equilateral triangle 

 with slightly convex sides. 



The peripheral cirri are composed of 25 to 28 segments, of which the longest 

 are from 2 to 3 times as long as the diameter of the much expanded, produced, and 

 overlapping distal ends [presumably about 4 times the median diameter A.M.C.], 

 and the last 7 to 10 are about as long as broad. 



The distal borders of the radials are even with the rim of the centrodorsal. The 

 IB^ are short, in lateral contact with their neighbors, and much incised in the median 

 line. The IBr 2 (axillaries) are rhombic, and nearly as long as broad. 



The ossicles of the IBr series and the first two brachials are in lateral apposition 

 and laterally flattened. The synarthrial tubercles are slightly developed. The ossicles 

 of the IBr series and the lower brachials have abruptly everted and finely spinous distal 

 edges; after the second syzygy this eversion of the distal edge of the brachials gradually 

 becomes more and more recumbent, taking the form of an overlapping of the distal 

 edges of the brachials which gradually dies away, disappearing after about the twentieth 

 brachial. The spinous eversion of the distal borders of the earlier brachials is somewhat 

 broader than in Trichometra cubensis, and does not stand out so high. 



The 10 arms are about 50 mm. long. The first brachial is about twice as broad as 

 long exteriorly, those of each arm pah* being inwardly united at the base. The second 

 brachials are much larger, irregularly quadrate. The first syzygial pair (third and 

 fourth brachials) and the following brachials are wedge-shaped, about as long as broad, 

 after the tenth becoming very obliquely wedge-shaped and considerably longer than 

 broad, the length gradually increasing distally. 



