84 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



393 (discussion; localities); Crinoids of the Indian Ocean, 1912, pp. 31, 33, 39 (identity); p. 103 

 (synonymy; summary of previous records); Die Fauna Siidwest-Australiens, vol. 4, Lief. 6, 

 1913, p. 310 (South Passage, Shark Bay, 9 m.; description); Smithsonian Misc. Coll., vol. 61, 

 No. 15, 1913, p. 20 (published references to specimens in British Museum; localities; characters 

 of the specimens). REICHENSPERQEB, Abh. Senck. Naturf. Ges., vol. 35, Heft 1, 1913, p. 82 

 (Aru Islands), p. 90 (Aru Islands, west of Ngaiguli, 14 m.; characters of the 2 specimens). 

 A. H. CLARK, Rec. Western Australian Mus., vol. 1, pt. 3, 1914, p. 123 (detailed comparison 

 with Z. elegans; specimens from northwest Australia and from Lewis Island positively identified 

 as this species); Internal. Rev. gesamt. Hydrobiol. und Hydrogr., 1915, p. 224 ff. (detailed 

 account of distribution in Australia).- F. W. CLARKE and WHEELER, U. S. Geol. Surv. Prof. 

 Pap. 90- L, 1915, p. 194 (inorganic constituents of skeleton). H. L. CLARK, Biol. Results Fish- 

 ing Exper. F. I. S. Endeavour, 1909-14, vol. 4, pt. 1, 1916, p. 19 (new locality; notes). HART- 

 METER, Mitt. zool. Mus. Berlin, vol. 8, Heft 2, 1916, p. 234 (W-Australien, Nos. 5966, 6136; 

 Mermaidstrasse, No. 5607) . F. W. CLARKE and WHEELER, U. S. Geol. Surv. Prof. Pap. 102, 

 1917, p. 21 (Aru Islands; inorganic constituents of skeleton). A. H. CLARK, Unstalked crinoids 

 of the Siboga-ftxped., 1918, p. 59 (in key; range), p. 60 (synonymy; notes; station 273), p. 275 

 (listed), pp. 277, 278 (inorganic constituents of skeleton) . GISLEN, Kungl. Svenska Vet. 

 Akad. Handl., vol. 59, No. 4, 1919, p. 3 (listed), p. 5 (station 13), pp. 19, 22, 23. A. H. CLARK, 

 Smithsonian 1 Misc. Coll., vol. 72, No. 7, 1921, p. 22 (food). F. W. CLARKE and WHEELER, 

 U. S. Geol. Surv. Prof. Pap. 124, 1922, p. 17 (inorganic constituents of skeleton). GISLEN, 

 Zool. Bidrag Uppsala, vol. 9, 1924, p. 278 (Brooine, Western Australia; shore; food), figs. 142, 

 143, p. 95 (pinnule articulations).- A. H. CLARK, Journ. Linn. Soc. (Zool.), vol. 36, 1929, p. 637 

 (Baudin Island, 8-15 fathoms).- GISLEN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 

 11, 1934, pp. 36, 37, 40. H. L. CLARK, Mem. Mus. Comp. Zool., vol. 55, 1938, p. 32 (Roebuck 

 Bay; Broome; Lagrange Bay, 5-8 fathoms; notes). 



Zygometra multiradiata A. H. CLARK, Smithsonian Misc. Coll., vol. 50, 1907, p. 348 (listed); Amer. 

 Journ. Sci., ser. 4, vol. 32, 1911, p. 130 (significance of distinctive characters); Die Fauna 

 Siidwest-Australiens, vol. 3, Lief. 13, 1911, p. 441 (Australian tropical species occurring south 

 to Dampier Archipelago and Cape York), p. 443 (range on east coast), p. 444 (range on west 

 coast), p. 446 (summary of west Australian records); Mem. Australian Mus., vol. 4, 1911, 

 p. 712 (identity with Hyponome sarsi), p. 717 (known from Australia), p. 721 (occurs south to 

 Cape York), p. 724 (peculiar to north Australia); p. 734 (in key), p. 761 (synonymy; charac- 

 ters; Australian records; range); Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 11 (synonym 

 of Z. microdiscus) ; Crinoids of the Indian Ocean, 1912, p. 3 (identity of Hyponome sarsi), p. 33 

 (synonym of microdiscus), p. 104 (synonymy; summary of known records); Rec. Western 

 Australian Mus., vol. 1, pt. 3, 1914, p. 123 (synonym of microdiscus). 



Zygometra miciodiscus A. H. CLARK, Amer. Journ. Sci., ser. 4, vol. 32, p. 130 (significance of dis- 

 tinctive characters). 



Zygometra mertoni REICHENSPERGER, Abh. Senck. naturf. Ges., vol. 35, Heft 1, 1913, p. 82 (Aru 

 Islands), p. 90 (description and comparisons; localities), fig. 6, p. 91 (proximal pinnules).- 

 A. H. CLARK, Unstalked crinoids of the Si&oja-Exped., 1918, p. 59, footnote 1 (synonym of 

 microdiscus). 



Zygometra microdisca H. L. CLARK, Echinoderm fauna of Torres Strait, 1921, pp. 5, 7 (history), 

 p. 20 (range). 



Zygometra cf. microdiscus GISLEN, Zool. Bidrag Uppsala, vol. 9, 1924, p. 271 (Hyponome sarsi; food). 



Diagnostic features. A large species with usually 65-100 arms from 85 to 145 

 mm. long, and the longest cirri with usually 45-70 segments; all, or nearly all, the 

 division series beyond the IBr series are 4(3 + 4) ; and the proximal pinnules are stout 

 at the base and very long, 20-32 mm. hi length, with 25-60 segments. 



Description. The centrodorsal is large and prominent, varying from thick dis- 

 coidal with a slightly convex dorsal pole about 3 mm. in diameter to more or less 

 hemispherical. The cirrus sockets are arranged in two to four (usually two or three) 

 irregular marginal rows. 



