A MONOGRAPH OF THE EXISTING CRINOIDS 79 



Dr. Clemens Hartlaub in 1895 divided the comatulids into two series, Series I, 

 with plated ambulacra, divided into two sections, a, with the elements of the IBr series 

 united by synarthry, including the Basicurva, Acoela, Spinifera, and Granulifera 

 groups, and 6, with the elements of the IBr series united by syzygy, including the 

 Elegans group only; and Series II, with unplated ambulacra, including the Eschrichti, 

 Milberti, Tenella, Palmata, and Savignyi groups. 



In my paper on new genera of recent crinoids published on April 11, 1908, the 

 new family Zygometridae was proposed, though not formally defined, and in it were 

 included the genera Eudiocrinus and Zygometra. 



In a paper published on May 14, 1908, though written before the one just 

 noticed, the family Zygometridae is given as including the genus Zygometra only, and 

 the range of this genus (which at that time included Catoptometra) is added. The 

 characters of the family are made evident in a key to the families of the Comatulida 

 having recent representatives. The genus Eudiocrinus, together with Decametro- 

 crinus, is included in the family Eudiocrinidae. At the time this paper was written 

 my idea of Eudiocrinus was based upon the species assigned to that genus and 

 described in detail and figured in the Challenger report, of some of which I had abun- 

 dant material collected by me in southern Japan. After the paper had been submitted 

 for publication, I received from Japan a specimen of a new species of Eudiocrinus 

 (variegatus) allied to the type species, E. indivisus, which showed that these forms 

 are allied to the species of Zygometra, whereas those described in the Challenger 

 report are of a wholly different nature. For the latter in the preceding paper the 

 genus Pentametrocrinus had been proposed and the new family Pentametrocrinidae 

 had been suggested to include this and the genus Decametrocrinus. 



This was explained in detail, the families Zygometridae and Pentametrocrinidae 

 were diagnosed, and the genus Eudiocrinus was redefined and the included species 

 listed, in a paper published on June 20, 1908. 



In 1909 the family Zygometridae was assigned by the author to the Comatulida 

 Oligophreata, together with the families Comasteridae, Himerometridae, Colobo- 

 metridae, Thalassometridae, and Tropiometridae. The status of the family Zygo- 

 metridae has since remained unchanged ; but in the present work the genus Eudiocrinus 

 has been removed from it, the special family Eudiocrinidae (redefined) being created 

 for its reception. 



KEY TO THE GENERA OF THE FAMILY ZYGOMETRIDAE 



a '. Segments in outer portion of cirri with prominent sharp dorsal spines (Philippine Islands and 

 Hongkong south to Sandon Bluffs, New South Wales, and to between Fremantle and Geraldton, 

 Western Australia, and westward to Ceylon ; 0-128 [7135] meters) Zygometra, p. 79. 



a*. No dorsal spines on distal cirrus segments (southern Japan, Bonin and Philippine Islands, 

 Hongkong, and southward to Lesser Sunda Islands; 25-914 meters), -Catoptometra, p. 125. 



Genus ZYGOMETRA A. H. Clark 



Hyponome LOVN, Forh. Skand. Naturf. M0de Christiania, vol. 10, 1868 (1869), p. LIV (description; 

 genotype, H. sarsii [*= detached visceral mass of Antedon microdiscus Bell, 1882]); Ann. Mag. 

 Nat. Hist., ser. 4, vol. 4, 1869, p. 159 (same); Can. Nat., new ser., vol. 4, 1869, p. 265 (same). 

 LtiTKEN, Vid. Medd. naturh. Foren. Kj0benhavn, 1869 (1870), pp. 185, 186, footnote, 187, 

 188, footnote. P. H. CARPENTER, Proc. Roy. Soc., vol. 28, 1879, p. 388 (identity with 

 Antedon) ; Nature, vol. 19, 1879, p. 450. PERKIER, Compt. Rend. Acad. Sci., vol. 96, 1883, p. 450. 

 P. H. CARPENTER, Ann. Mag. Nat. Hist., ser. 5, vol. 11, 1883, p. 336 (identity); Chattenger 



