A MONOGRAPH OF THE EXISTING CRINOIDS 23 



Genus DAIDALOMETRA A. H. Clark 



Anledon (part) A. H. CLARK, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 137. 



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



Stcnometra (part) A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 15. 



Stiremelra (part) A. H. CLARK, Die Fauna Siidwest-Australiens, vol. 3, Lief. 13, 1911, pp. 440, 443. 



Daidalometra A. H. CLARK, Journ. Washington Acad. Sci., vol. 5, No. 6, 1915, p. 215 (no diagnosis; 

 name used in combination with [Antedon] hana); vol. 6, No. 5, 1916, p. 116 (diagnosis; genotype 

 Antedon hana A. H. Clark, 1907; comparison of arms with those of Stenomelra) ; Unstalked 

 crinoids of the Sj'6o0a-Exped., 1918, p. 146 (in key; range), p. 147 (same), p. 157 (key to the 

 included species). GISLN, Nova Acta Ilcg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, pp. 9, 

 118; Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, pp. 18, 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 10-18 (usually 10-15) in number, 60-65 mm. long; 

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

 slender, and delicate, 20-24 mm. long with 32-75 segments, and are arranged in 10 

 columns on a small conical or truncated conical centrodorsal. 



Geographical range. From Port Denison, Queensland, to Timor and northward to 

 southwestern Japan. 



Bathymetrical range. From 22 to 548 meters. 



Remarks. The genus Daidalometra is very closely related to Stenometra and per- 

 haps should not be separated from it. There appear to be no real differences between 

 the two other than in the number of arms, and in this feature there is a certain amount of 

 overlapping between occasional individuals of some species. The three species of 

 Daidalometra appear to be well characterized, although all three are known from only a 

 small number of individuals. 



History. The genus Daidaometra was established in 1916 with the genotype Ante- 

 don hana A. H. Clark, 1907. The two species included in it at the time of the original 

 description were D. hana and D. acuta. In 1918 a key to the two included species was 

 given, with acuta regarded as a synonym of the earlier arachnoides. 



In 1922 in his description of Stenometra dentata Prof. Torsten Gislen wrote that this 

 new species approaches Daidalometra (hana), a genus properly distinguished from 

 Stenometra only by a smaller number of arms. He said that S. dentata is to a certain 

 extent a transition between these two genera. 



KEY TO THE SPECIES IN THE GENUS DAIDALOMETRA 



a 1 . Cirri short, not more than half the length of the arms, with not more than 65 segments; arms 60-65 



mm. long. 



6 1 . Cirri with 49-65 segments; division series and proximal brachials with a narrow, sharp, and high 

 median carination, the ossicles with everted and spinous edges; 10-18 (usually 10-13) arms 

 (Queensland to Timor and northward to the Sulu [Jol6] Archipelago; 22-118 meters). 



arachnoides (p. 25) 



6*. Cirri with 32-39 segments; carination of the division series and arm bases low with a rounded 

 crest; edges of the elements of the division series and proximal brachials little modified; 10 



arms (Zamboanga, Mindanao; about 548 meters) eurymedon (p. 24) 



a?. Cirri longer, more than two-thirds of the length of the arms, 40-45 mm. long with 68-77 segments; 

 arms 10-11, 60 mm. long (southwestern Japan; 196-254 meters) hana (p. 27) 



