A MONOGRAPH OF THE EXISTING CRINOIDS 193 



average depth about the same, but no species descend so deep or come so near the surface), p. 42 

 (raised to family rank from a subfamily), pp. 45, 49, 51, 53 (in keys), p. 60 (key to the included 

 genera).— Hartlaub, Mem. Mus. Comp. Zool., vol. 27, No. 4, 1912, p. 286 (discussion).— 

 Springer and Clark, Zittel-Eastman's Paleontology, 1913, p. 236 (in the Oligophreata).— A. H. 

 Clark, Bull. Inst. Oceanographique, Monaco, No. 294, 1914, pp. 7, 8 (temperature relations); 

 Journ. Washington Acad. Sci., vol. 4, No. 19, 1914, pp. 559-563 (correlation of geographical and 

 bathymetrical ranges); No. 20, 1914, p. 582 (relation to temperature of habitat); Internat. Rev. 

 gesamt. Hydrobiol. und Hydrogr., 1914, pp. 4 and following (Atlantic and corresponding Indo- 

 Pacific genera) ; Die Crinoiden der Antarktis, 1915, p. 132 (covering plates compared with those in 

 the Heliometrinae), p. 164 (represented in South Africa by Pachylomelra sclaleri); Amer. Journ. 

 Sci., vol. 40, 1915, p. 67 (detailed philosophical discussion of bathymetrical range); Smithsonian 

 Misc. Coll., vol. 65, No. 10, 1915, pp. 43 and following (phylogenetical study); Unstalked crinoids 

 of the Siboga Expe'd., 1918, p. 171 (key to the included genera); Journ. Washington Acad. Sci., 

 Vol. 9, No. 5, 1919, p. 136 (arm bases compared with those of Holopus) ; Univ. Iowa Studies in Nat. 

 Hist., vol. 9,'No. 5, 1921, p. 12 (represented in the West Indies) ; Smithsonian Misc. Coll., vol. 72, 

 No. 7, 1921,' pp. 3, 13— Gislen, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, pp. 

 10 "ii9— AH Clark The Danish /ngoi!/-Exped., vol. 4, No. 5, Crinoidea, 1923, p. 40.— Gislen, 

 Zool. Bidrag Uppsala, vol. 9, 1924, p. 19 (arm structure), pp. 42, 44, 73, 80, 84, 85, 88, 90, 94, 100, 

 231 239, 280, 284; Vid. Medd. Dansk Naturh. Foren. K"0benhavn, vol. 83, 1927, pp. 33, 38; 

 Ark Zool. vol. 19,' No. 32, Feb. 20, 1928, pp. 8, 9— A. H. Clark, Journ. Linn. Soc. (Zool.), vol. 

 36 No 249 April 1929, p. 655.— Gislen, Vid. Medd. Dansk Nat. Foren. R"0benhavn, vol. 93, 

 October 26, 1933, pp. 481, 482.— A. H. Clark, Treubia, vol. 14, livr. 2, December 1933, p. 214.— 

 Gislen Kungl. Fysiograf. Sallsks. Handl., new ser., vol. 45, No. 11, 1934, pp. 18, 20, 22, 23 — 

 A H Clark, John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1936, 1937, pp. 101, 

 103 —Gislen Kungl. Svenska Vet.-Akad. Handl., ser. 3, vol. 17, No. 2, October 3, 1938, pp. 4, 

 18.— H. L. Clark, Mem. Soc. Cubana Hist. Nat., vol. 15, No. 1, May 1941, p. 9.— A. H. Clark, 

 Bernice P. Bishop Mus. Bull. 195, 1949, p. 75. 

 Charitometriden A. H. Clark, Die Crinoiden der Antarktis, 1915, p. 192 (species and genera of this 

 family especially characteristic of the Intermediate fauna). 



Diagnosis.— A family of the superfamily Tropiometrida in which the ventral 

 perisome of the pinnules is protected by well-developed and conspicuous side and 

 covering plates easily visible with a hand lens; P, and P 2 are simdar (in small species 

 P 2 may be like P 3 ), of about the same length as the following pinnules, sometimes some- 

 what longer or shorter, but more slender and flexible and composed of a large number 

 of short segments; and the cirri are short, stout, and strongly curved, composed of 

 usually less than 25 segments of which the outer are little, if at all, shorter than the 

 earlier and bear no dorsal processes though they may be carinate or rise into low 

 broadly rounded tubercles at the distal end; there is no transition segment and all the 

 segments are simdarly dull in color. 



Geographical range.— From southern Japan, the Hawaiian Islands, *iji, the Ker- 

 madecllslands, the Sahul Bank, and Timor westward to east Africa, from Sokotra 

 southward to East London; St. Helena; from the Yucatan Bank, the Honda Keys 

 northern Cuba, and the southern Bahamas eastward and southward to Barbados and 



Grenada. 



Bathymetrical range.— From 55 to 2,194 meters. 



Thermal range.— From 4.17° to 18.20° C. 



Remarks.-Bec&usc of the singularly uniform structure of all the species in this 

 family, particularly the similarity of the oral pinnules and of the cirri throughout the 

 delimitation of natural genera within the group has proved to be a matter of no little 

 difficulty. Twelve genera have been established, many of them based on characters 



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