82 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



KEY TO THE SPECIES IK THE GENUS ZYGOMETRA 



o' . More than 40 cirrus segments; more than 35 (usually 40 or more) arms. 



6 1 . More than 40 (65-100) arms; all, or most, of the IIIBr and following division series 4(3 + 4); 

 usually 45-55 cirrus segments; proximal pinnules very stout and very long (20-32 mm.), 

 tapering to a slender and flagellate tip; cirri very long and stout (Aru Islands and northern 

 Australia south to Shark Bay, Western Australia, and Port Curtis, Queensland; 0-128 



[7135] meters) microdiscus (p. 82) 



b 2 . About 40 (usually 35-45) arms; most of the IIIBr and following division series 2; usually 35- 

 45 cirrus segments; proximal pinnules of moderate length (14-18 mm.) and not especially 

 stout; cirri not especially long or stout (northern Australia south to between Fremantle 

 and Geraldton, Western Australia, and Sandon Bluffs, New South Wales; Amboina; 0-89 



meters) elegans (p. 98) 



o 2 . Less than 40 cirrus segments; less than 40 arms. 



6'. More than 10 arms; syzygy between the elements of the IBr series perfect. 

 c 1 . Cirri moderately long, with usually 25-30 segments; usually 25-35 arms. 



d l . Distal edges of radials and proximal and distal borders of the elements of the division 

 series and first 2 brachials plain and unmodified (Mergui Archipelago to Lesser Sunda 

 Islands, Holothuria Bank, the Moluccas, Salawatti, Philippines, and Hongkong; 0-73 



meters) comata (p. 110) 



<i 2 . Distal edges of radials, proximal and distal borders of the elements of the division series, 

 and to a lesser extent the proximal and distal ends of the first 2 brachials thickened and 

 everted.this eversion being finely scalloped or tuberculated (?Ceylon) . andromeda (p. 1 10) 

 c 2 . Cirri short and rather stout, strongly recurved in distal half, with not more than 21 segments; 

 not more than 21 arms (Aru Islands and northern Australia, south to Port Curtis, Queens- 

 land; 0-50 meters) punctata (p. 120) 



b 2 . Only 10 arms; syzygy between the elements of the IBr series imperfect, the radiating ridges 

 being developed only on peripheral half of joint faces; arms 50 mm. long; cirri XII, 20-21, 

 12 mm. long (Philippines; 33 meters) pristina (p. 123) 



ZYGOMETRA MICRODISCUS (Bell) 



PLATE 1, FIGURES 1, 2; PLATE 2, FIGURES 3, 4, 6 



[See also vol. 1, pt. 1, fig. 332 (cirrus), p. 283; pt. 2, fig. 136 (arm base), p. 79; pi. 13, figs. 1045. 1052 

 (pinnules) ; pi. 14, fig. 1060 (pinnule); pi. 25, figs. 1155-1157 (disk).] 



Hyponome sarsi LOVEN, Forh. Skand. Naturf. M0de Christiania, July 1868 (1869), p. LIV (descrip- 

 tion and affinities; Cape York, Torres Strait) ; Of v. Vet.-Akad. Forh., 1869, pp. 729-731; Compt. 

 Rend. Acad. Sci. vol. 69, Sept. 1869, pp. 711, 712. BILLINGS, Can. Nat., new ser., vol. 4, 1869, 

 p. 270. LOVEN, Can. Nat., new ser., vol. 4, 1869, p. 265 (detailed description; Cape York); 

 Ann. Mag. Nat. Hist., ser. 4, vol. 4, 1869, p. 159. LUTKEN, Vid. Medd. Naturh. Foren. Kb- 

 enhavn, 1869, pp. 184, 185, 186, footnote (discussion) ; Can. Nat., new ser., vol. 4, 1869, p. 267. 

 WTVILLE THOMSON, Proc. Roy. Soc. Edinburgh, vol. 7, 1872, p. 417. P. H. CARPENTER, Proc. 

 Roy. Soc., vol. 28, 1879, p. 388. DE LORIOL, Pal6ontologie francaise, Terraine jurassiques, vol. 

 11, pt. 2, 1889, p. 436. GISLEN, Zool. Bidrag Uppsala, vol. 9, 1924, p. 271 (food). 



Hyponome sarsii LOVEN, Amer. Journ. Sci., ser. 2, vol. 48, 1869, p. 429. WTVILLE THOMSON, Proc. 

 Roy. Soc. Edinburgh, vol. 7, 1871, p. 417. SCHLUTER, Zeitschr. deutschen geol. Ges., vol. 30, 

 Heft 1, 1878, p. 29. PERRIER, Compt. Rend. Acad., Sci., vol. 96, 1883, p. 450; Ann. Mag. Nat. 

 Hist., ser. 5, vol. 11, 1883, p. 223. P. H. CARPENTER, Ann. Mag. Nat. Hist., ser. 5, vol. 11, 



1883, p. 336; Proc. Roy. Soc. Edinburgh, vol. 12, 1884, p. 369. LOCKINGTON, Standard Nat. 

 Hist., vol. 1, 1884, p. 140. P. H. CARPENTER, Challenger Reports, Zoology, vol. 11, pt. 32, 



1884, pp. 67, 85, 166; vol. 26, pt. 60, 1888, p. 97 (identity); Journ. Linn. Soc. (Zool.), vol. 24, 

 1891, p. 45 (identity). HARTLAUB, Nova Acta Acad. German., vol. 58, No. 1, 1891, p. 25. 

 NEVIANI, Riv. Ital. Sci. Nat., ann. 11, 1891, fasc. 2, p. 6. A. H. CLARK, Smithsonian Misc. 

 Coll., vol. 50, 1907, p. 348 (identity); Mem. Australian Mus., vol. 4, 1911, p. 761 (same); 

 Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 1 (history; identity), p. 11 (specific identity) ; 



