A MONOGRAPH OF THE EXISTING CRINOIDS 7 



Genus STENOMETRA A. H. Clark 



Antedon (part) P. H. CARPENTER, Challenger Reports, Zool., vol. 26, pt. 60, 1888, p. 215, and following 

 authors. 



Thalassomctra (part) A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 360. 



Stenometra A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 14 (diagnosis; genotype 

 Antedon quinquecostata P. H. Carpenter, 1888); Vid. Medd. Naturhist. Foren. K0benhavn, 1909, 

 p. 193 (probably occurs at Singapore); Crinoids of the Indian Ocean, 1912, p. 9 (absent from 

 Australia), p. 11 (absent from the west coast of the Malay Peninsula, the Andamans, and farther 

 west), p. 24 (range), p. 59 (in key), p. 209 (original reference; type); Journ. Washington Acad. 

 Sci., vol. 6, No. 5, 1916, p. 116 (comparison of arms with those of Daidalometra); Unstalked 

 crinoids of the Siboga-E,xped., 1918, p. 148 (in key; range), p. 156 (key to the included species). 

 GISLEN, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, pp. 9, 115, 118; Ark. 

 Zool., vol. 19, No. 32, Feb. 20, 1928, p. 7. A. H. CLARK, Journ. Linn. Soc. (Zool.), vol. 36, No. 

 249, April 1929, pp. 647, 649. GISLEN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 

 1934, p. 20. 



Diagnosis. A genus of Thalassometridae in which the division series, which are 

 all 2, and arms are laterally compressed and sharply carinate, gablelike in cross section, 

 the brachial carination being produced into high crests or broad overlapping spines; 

 the arms in fully developed individuals are normally 20 in number, 65-100 mm. long; 

 there is no appreciable expansion of the earlier segments of the genital pinnules; PI 

 resembles P 2 but is somewhat longer and proportionately stouter; the cirri are long, 

 slender, and delicate, 25-75 mm. long with 50-90 segments, and are arranged in 10 

 columns on the small conical or truncated conical centrodorsal. 



Geographical range. From Timor and the Moluccas north to the Bonin Islands 

 and southern Japan from the Korean Straits to Sagami Bay. 



Bathymetrical range. From 141 (?95) to 457 meters. 



Thermal range. From 11.3 to 15.9 C. 



Remarks. The genus Stenometra as herein understood includes four species. One 

 of these, the very spiny S. dentata from the Bonin Islands, appears to be quite distinct 

 from the others, although S. snelliusi from Ceram is to a certain extent intermediate 

 between it and the other two. Stenometra diadema is the Japanese representative of 

 the East Indian S. quinquecostata from which it seems always to be distinguishable 

 though the differences are slight. 



History. The first known species of this genus was described under the name of 

 Antedon quinquecostata by Dr. P. H. Carpenter in 1888. It was transferred to the new 

 genus Thalassometra upon its establishment in 1907. In 1909 I proposed the genus 

 Stenometra with Antedon quinquecostata P. H. Carpenter, 1888, as the genotype, listing 

 as the included species conifera Hartlaub, diadema A. H. Clark, hana A. H. Clark, and 

 quinquecostata P. H. Carpenter, all of which had been originally described in the genus 

 Antedon. Later in 1909 conifera was transferred to the genus Cosmiometra, and in 1916 

 hana was selected as the genotype of the new genus Daidalometra, the combination 

 Daidalometra hana having appeared without any explanation in 1915. 



KEY TO THE SPECIES IN THE GENUS STENOMETRA 



a 1 . Proximal and distal edges of the elements of the division series and lower brachials not swollen or 

 everted, and sparsely or not at all spinous or denticulate; few or no spines on the lateral portions 

 of the elements of the division series and arm bases; cirri slender, the longest segments at least 

 twice as long as broad. 



