76 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



brachials and exceedingly fragile, the proximal pinnules are either absent or do not 

 differ appreciably from those succeeding, and there is no gap in the succession of 

 pinnules. 



In both the Mariametrida and the Macrophreata there are species in which one or 

 more of the proximal pinnules, most commonly the first inner pinnule (P a ), are absent. 

 Most of these species in the Mariametrida have 10 arms only. In the Mariametrida 

 the species with deficient pinnulation are all included in the single family Colobometri- 

 dae. They are very easily distinguished from all the species in the Macrophreata by 

 having on the dorsal surface of the cirrus segments either a serrate transverse ridge, 

 or two tubercles or spines situated side by side, or a transverse row of 3 or 4 spines or 

 tubercles; the dorsal surface of the cirrus segments in the Macrophreata is either 

 broadly or more or less sharply rounded, or else is carinate in the middorsal line. 



As the great majority of the 10-armed species of Mariametrida belong to the family 

 Colobometridae, in the case of doubtful 10-armed forms the dorsal surface of the cirrus 

 segments should always be the first feature examined. 



Family ZYGOMETRIDAE A. H. Clark 



Series I of Antedon P. H. CARPENTER, Challenger Reports, Zoology, voL 26, pt. 60, 1888, p. 94; Jouru. 

 Linn. Soc. (Zool.), vol. 21, 1889, p. 304. 



Elegans group [of Antedon] P. H. CARPENTER, Challenger Reports, Zoology, vol. 26, pt. 60, 1888, 

 p. 266; Journ. Linn. Soc. (Zool.), vol. 21, 1889, pp. 304, 307. HARTLAUB, Bull. Mus. Comp. 

 Zool., vol. 27, 1895, p. 136 (discussion), p. 137 (structural position). A. H. CLARK, Proc. 

 U. S. Nat. Mus., vol. 33, 1907, pp. 127, 130 (descriptions of new species); Smithsonian Misc. 

 Coll., vol. 50, 1907, p. 348 (the equivalent of Zygometra, gen. nov.). 



Zygometridae A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 135 (includes Eudiocrinus 

 and Zygometra); Proc. U. S. Nat. Mus., vol. 34, 1908, p. 210 (in key), p. 211 (includes Zygo- 

 metra; range; not represented in the Hawaiian Islands), p. 212 (range of included genus), p. 276 

 (revised description; range; includes Zygometra and Eudiocrinus); vol. 35, 1908, p. 118, figs. 

 14, 15, p. 119, fig. 16 (arm structure); Amer. Nat., vol. 42, 1908, p. 541 (characteristic of Indo- 

 Pacific-Japanese fauna), p. 722 (ecology), p. 725 (color); Geogr. Journ., vol. 32, 1908, p. 602 

 (characteristic of Indo-Pacific-Japanese region), p. 605 (ecology); Proc. Biol. Soc. Washington, 

 vol. 22, 1909, p. 2 (modification of cirri and lower pinnules as in the Thalassometridae) ; Amer. 

 Nat., vol. 43, 1909, p. 256 (absence from the Red Sea noteworthy); Proc. U. S. Nat. Mus., 

 vol. 36, 1909, p. 361 (part of Antedon as used by P. H. Carpenter) ; Proc. Biol. Soc. Washington, 

 vol. 22, 1909, p. 174 (only family witn a syzygy in the IBr series; referred to Comatulida Oligo- 

 phreata); Amer. Nat., vol. 43, 1909, p. 581 (arm structure); Vid. Medd. Nat. Foren. K0ben- 

 havn, 1909, p. 119 (occurs at Singapore; has large eggs that presumably develop rapidly; 

 ecology); Amer. Journ. Sci., vol. 29, 1909, p. 43 (articular facet of a radial, showing develop- 

 ment); Proc. U. S. Nat. Mus., vol. 39, 1911, p. 538 (articulation between elements of IBr series 

 really a remarkably perfect pseudosyzygy, as demonstrated by Zygometra pristina, sp. nov); 

 vol. 40, 1911, p. 649 (referred to Oligophreata) ; Die Fauna Siidwest Australiens, vol. 3, Lief. 

 13, 1911, p. 438 (1 genus and 3 species in Australia); Mem. Australian Mus., vol. 4, 1911, p. 

 717 (proportion of the species of this family in the fauna of Australia as known to P. H. Car- 

 penter), p. 720 (proportion of the species of this genus in the Australian fauna), p. 725 (Eudio- 

 crinus and Catoptomelra absent from Australia; this family disproportionately developed in 

 Australia), p. 728 (closely related to the Himerometridae), p. 729 (in key), p. 731 (1 genus in 

 Australia); Crinoids of the Indian Ocean, 1912, p. 3 (Hyponome sarsii the detached visceral 

 mass of some species of this family), p. 6 (confined to the East Indian region; number of included 

 genera and species), p. 11 (occurs west to the west coast of the Malay Peninsula and the 

 Andamans), p. 14 (very restricted distribution; littoral), p. 21 (distribution in detail), p. 42 

 (closely related to the Himerometridae), pp. 44, 45, 47, 48, 50, 52 (in keys), p. 56 (key to the 



