340 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



having no dorsal processes. The radials are concealed. The IBrj are short and rather 

 convex in the center. The IBr 2 (axillaries) are short and widely pentagonal with 

 slight backward projections. The elements of the IBr series and the first two brachials 

 are sharply flattened laterally with straight edges and the margins of the dorsal surface 

 flattened. The 10 arms are perhaps 70 mm. long. The lower brachials are nearly 

 oblong and those following are smooth, short, and bluntly wedge-shaped, gradually 

 becoming more oblong about the middle of the arm. Syzygies occur between brachials 

 3 + 4, again from between brachials 13 + 14 to between brachials 14 + 15, and distally at 

 intervals of from 5 to 7 muscular articulations. P! is rather longer than P a , and the 

 following pinnules increase in length to P 3 and P c , which consist of about a dozen 

 segments, the lowest of which are broad and slightly carinate. P 4 and P d are smaller 

 with relatively longer segments, and the following pinnules slowly increase in length. 

 Sacculi are apparently absent. The color in alcohol is very light brown. 



Gislen examined the type specimen of denticulata at the British Museum in 1925. 

 He said there is a small opposing spine, as was shown in Carpenter's figure. He sug- 

 gested that probably the specimen from Siboga station 167 belongs to another species, 

 as the cirri seem to be evenly tapering without any opposing spine. 



Localities. Challenger station 190; Arafura Sea, southeast of the Aru Islands 

 (lat. 856' S., long. 13605' E.); 90 meters; green mud; September 12, 1874 [P. H. 

 Carpenter, 1888; Bell, 1888; Hartlaub, 1891; A. H. Clark, 1907, 1911, 1912, 1913] 

 (1,B.M.). 



Siboga station 167; south of Salawatti, off the western end of New Guinea (lat. 

 235'30" S., long. 13126'12" E.); 95 meters; August 22, 1899 [A. H. Clark, 1918] (1, 

 Amsterdam Mus.). 



Geographical range. Known only from the Arafura Sea and from off the western 

 end of New Guinea. 



Bathymetrical range. The two records are 90 and 95 meters. 



History. This species was first described in 1888 by P. H. Carpenter under the 

 name of Antedon denticulata from a single specimen from Challenger station 190. In 

 my first revision of the old genus Antedon published in 1907 denticulata was placed in 

 the new genus Nanometra. In 1911 it was transferred to the genus Amphimetra. 

 In 1918 I referred to this species and described a second specimen from Siboga station 

 167, at the same creating the new genus Homalometra for its reception. Gislen in 1928 

 suggested that probably the Siboga specimen represents a species different from 

 that described by Carpenter. 



Genus AMPHIMETRA A. H. Clark 



Comatula (part) GUERIN-MENEVILLE, Iconographie du regne animal de G. Cuvier, 1828-1837, 



pi. 1, figs. 2, 2a, and following authors. 



Alecto (part) J. MULLER, Monatsb. Preuss. Akad. Wiss., 1841, p. 184. 

 Comatula (Alecto) (part) J. MULLER, Monatsb. Preuss. Akad. Wiss., 1846, p. 178. 

 Antedon (part) WYVILLE THOMSON, Philos. Trans. Roy. Soc., vol. 155, 1865, p. 537, and following 



authors. 



Antedon (Comatula) (part) POURTALES, Bull. Mus. Comp. Zool., vol. 1, 1869, p. 356. 

 Himeromelra (part) A. H. CLARK, Smithsonian Misc. Coll., vol. 50, 1907, p. 356. 

 Oligometra (part) A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 126; vol. 22, 1909, 



pp. 7, 42. 



