388 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



and in those succeeding the length very gradually decreases so that the distal seg- 

 ments are about one-third again as broad as long. The tenth and following segments 

 have well-developed dorsal spines. 



The disk is completely covered with a pavement of small plates. 



The synarthrial tubercles between the elements of the IBr series and the first 

 two brachials are extravagantly developed, as in Perometra diomedeae, giving the 

 animal a very characteristic appearance. 



The 10 arms are 80 mm. long and resemble those of A. discoidea. 



The segments of all the proximal pinnules are about as long as broad. PI is 7 

 mm. long, very slender, with 20 segments. P 2 is 7 mm. long, stouter than PI, with 17 

 segments. P 3 is similar to P 2 but is only 5 mm. long, with 16 segments. P 4 and the 

 following pinnules are less stout than P 2 and P 3 though stouter than PI, 5 mm. long, 

 with 13 segments. 



The color in alcohol varies from nearly white to dark brown, with the perisome 

 darker. The cirri of the lighter specimens are usually purplish. 



Notes. Of the four specimens recorded in 1909 one has the arms 90 mm. long 

 and the cirri XVII, 30-33, from 20 to 23 mm. long. It is white, with the perisome 

 brownish purple and the cirri becoming light purplish distally. Another is similar 

 but is yellow-brown. A third has the arms 80 mm. long and the cirri XIV, 30-33, 

 from 23 to 27 mm. long; in color it is brownish white. The fourth is smaller and is 

 light bluish gray. 



Other specimens not previously recorded show the following characters: (1) 

 The arms are about 95 mm. long, and the cirri are XIX, 33-36, from 22 to 24 mm. 

 long; the dorsal pole of the centrodorsal is convex, 3.5 mm. in diameter. (2) The 

 arms are 95 mm. long, and the cirri are XVI, 28-34, from 22 to 24 mm. long; the 

 dorsal pole of the centrodorsal is flat, 4 mm. in diameter. (3) The arms are 115 

 mm. long and the cirri are XVI, 29-33, 25 mm. long; the dorsal pole of the centro- 

 dorsal is convex, 4.0 to 4.5 mm. in diameter. (4) The arms are 120 mm. long, and 

 the cirri are XVI, 34-39, 25 mm. long; the dorsal pole of the centrodorsal is convex, 

 3.5 mm. in diameter. (5) The arms are 95 mm. long, and the cirri are XIV, 38-40, 

 from 25 to 30 mm, long; the dorsal pole of the centrodorsal is slightly convex, 3.5 

 mm. in diameter. (6) The arms are 80 mm. long. (7) The arms are 75 mm. long. 

 (8) The arms are 40 mm. long. 



Locality Singapore; Svend Gad [A. H. Clark, 1908, 1909, 1912, 1918] (63, 

 U.S.N.M., 36197, 36260, 36261, E. 1083; C.M.). Same, 13 meters; December 12, 

 1898 [A. H. Clark, 1929] (7, B. M.). 



History. This species was first described as Himerometra ensifor in 1908 from a 

 specimen from Singapore in the collection of the Copenhagen Museum that had been 

 collected by the Danish consul at that port, Svend Gad. 



In a revision of the family Himerometridae published in 1909 this species was 

 referred to the new genus Amphimetra, being listed through error as Amphimetra 

 ensiformis. Later hi 1909 four additional specimens were recorded from Singapore, 

 and notes on them were given. 



It was listed in my memoir on the crinoids of the Indian Ocean (1912) and in 

 my report upon the unstalked crinoids of the Siboga expedition (1918), and in both 



