A MONOGRAPH OF THE EXISTING CRINOIDS 537 



Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 76. — H. L. Clark, Ann. 

 South African Mus., vol. 13, pt. 7, 1923, p. 233 (questions desirability of recognizing the genus). — 

 Gisl£n, Kungl. Svenska Vet.-Akad. Handl., ser. 3, vol. 17, No. 2, 1938, p. 4. 

 Liparometra (part) H. L. Clark, Ann. South African Mus., vol. 13, pt. 7, 1923, p. 232. 



Diagnosis. — A genus of Mariametridae in which P 8 is the longest and largest 

 pinnule, usually markedly longer than P 2 or P 4 , though sometimes not greatly longer 

 (and in young or undeveloped individuals or od undeveloped arms occasionally 

 shorter), and tapers gradually to a delicate tip; the division series are usually in close 

 lateral apposition with more or less flattened sides, less commonly just in contact 

 or even free laterally with the sides slightly or even not at all flattened; the cirri are 

 of moderate length with 22-43 segments, of which the outer are simply carinate 

 dorsally or bear more or less strongly developed dorsal spines or tubercles; and the 

 dorsal surface of the division series is smooth, without ornamentation. 



Geographical range. — From southern Japan, from the Korean Straits to Sagami 

 Bay, to Hongkong, the Philippines, the Pelew and Admiralty Islands, New Guinea, 

 and Amboina, and westward to Madagascar and the east coast of Africa from Lamu, 

 Kenya, southward to Durnford Point, Zululand. 



Bathymetrical range. — From the shoreline down to 164 meters. The species are 

 epsecially characteristic of the littoral and sublittoral zones, and all but one (ciliata) 

 have been taken in shore collecting. 



Remarks. — The genus Dichrometra as herein considered includes seven species, 

 all of which are rare and none of which are adequately known. These seven species 

 are all very much alike, and the differences between them are slight. Three of the 

 seven species, flagellata, tenuicirra, and ajra, form a group more or less distinct from 

 the others. Although these three are the easiest to recognize, they are probably 

 merely local varieties of the same form. Of the remaining four species, bimacvlata 

 and stylifer seems to have much in common, and doderleini and ciliata are certainly 

 closely allied. 



History. — The genus Dichrometra was established by me in 1909 with the genotype 

 Alecto flagellata J. Miiller, 1841, to include 20 forms that previously had been assigned 

 to the genus Himerometra. 



In 1913 Dichrometra, as originally constituted, was restricted by the removal of 

 3 forms to the new genus Liparometra, 11 to the new genus Lamprometra, and 1 to 

 Oxymetra, leaving 5 forms of which one (marginata) is now placed in Stephanometra 

 and another (subcarinata) in Mariametra. To the three forms remaining (bimaculata, 

 elongata, and flagellata) were added doderleini and stylifer, omitted from the original 

 list, and ajra, ciliata, pulcher, and tenuicirra, described after the original list was 

 published. 



KEY TO THE SPECKS IN THE GENUS DICHROMETRA 



a 1 . Cirri slender, with longest earlier segments from two to two and one-half times as long as broad 

 and distal segments about half again as long as broad; 16-26 arms 70-80 mm. long; cirri 

 XIX-XXVIII, 25-28, 20-25 mm. long (Java Sea, from between southeastern Borneo and 

 eastern Java to north of western Java; 0-88 meters) tenuicirra (p. 556) 



a*. Cirri stouter, with longest earlier segments not more than one-third again as long as broad and 

 distal segments broader than long, or at least not appreciably longer than broad. 

 208244—41 35 



