A MONOGRAPH OF THE EXISTING CRINOIDS 337 



basing his description upon a specimen which he found on the sand flat on the southern 

 side of Friday Island, Torres Strait. 



In 1921 Dr. Clark said that the holotype of this species does not seem to be one 

 of the Zygometridae at all. There are no traces of syzygies or of pseudosyzygies in 

 the IBr series, the joints being perfectly normal muscular articulations. The IBr, 

 are not short and bandlike, as in Zygometra punctata, but the width is only a little more 

 than twice the length. The IBr 2 (axillaries) are pentagonal, not twice as broad as 

 long. The radials are not concealed by the centrodorsal. None of the basal segments 

 of the cirri are twice as broad as long. Finally, the color is quite unlike that of Z. 

 punctata or any other member of that genus; there is no white save on the cirri, which 

 are more or less light colored. He remarked that this puzzling little comatulid (M.C.Z. 

 587) is very probably a young individual not yet revealing its species characters, and 

 that it may possibly be a young Amphimetra. He added that since examining it I 

 had decided that it is altogether too young for determination. 



Genus HOMALOMETRA A. H. Clark 



Antedon (part) P. H. Carpenter, Challenger Reports, Zoology, vol. 26, pt. 60, 18S8, p. 130, and 



following authors. 

 Nanomelra (part) A. H. Clark, Smithsonian Misc. Coll., vol. 50, 1907, p. 349. 

 Amphimetra (part) A. H. Clark, Die Fauna Sudwest-Australiens, vol. 3, Lief. 13, 1911, p. 441. 

 Homalometra A. H. Clark, Unstalked crinoids of the Siboga-Hxped., 1918, pp. 72, 73 (in key; range). — 



Gislen, Kungl. Fysiogr. Sallsk. llandl., new ser., vol. 45, No. 11, 1934, pp. 18, 22, 44, 46. 



Diagnosis. — A genus of Himerometridae in which the arms are 10 or 11 in num- 

 ber, the IIBr series when present being 4(3 + 4), and the cirri are slender, only very 

 slightly curved, slowly tapering distally, and composed of 25-30 segments, of which 

 all but the basal are markedly longer than broad and of which the distal are smooth 

 dorsally, being quite without dorsal spines or tubercles. 



Geographical range. — From the Arafura Sea to the western end of New Guinea. 



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



Remarks. — The genus Homalometra is very closely related both to Heterometra 

 and to Amphimetra, but it is at once distinguished for both by its peculiar cirri, 

 The slenderness and delicacy of these organs, combined with the rather small size 

 of the animal, give it very much the appearance of a macrophreate form. 



The genus Homalometra bears somewhat the same relation to Amphimetra that 

 Craspedometra does to Heterometra. The single species of Craspedometra may be 

 considered as a stout and rather large species of Heterometra with tapering sharp 

 pointed and smooth cirri, while the single species of Homalometra may be regarded 

 as a slender and rather small species of Amphimetra with tapering and smooth cirri. 



History. — In describing the single species of Homalometra in 1888 Dr. P. H. 

 Carpenter referred it to Antedon. In 1907 when I revised the old genus Antedon, 

 Carpenter's Antedon denticulata was referred to the new genus Nanometra. After 

 an examination of the type specimen in the British Museum in 1910, the species 

 was assigned, in 1911, to the genus Amphimetra. 



The generic name Homalometra first appeared in the report on the unstalked 

 crinoids of the Siboga expedition published in 1918. It was not formally defined, 

 but the name was inserted in the key to the genera of the family Himcroir.etrida-.\ 



