A MONOGRAPH OF THE EXISTING CRINOIDS 273 



and its significance); Unstalked crinoids of the Si6ojo-Exped., 1918, p. ix (relationship with 

 T. afro), p. 131 (In key; range). — Mortensen, Studies in the development of crinoids, 1920, p. 

 26 (occurrence at Misaki). — A. H. Clark, Smithsonian Misc. Coll., vol. 72, No. 7, 1921, 

 pi. 1, fig. 9 (nerves). — Gisl^n, Nova Acta Reg. Soe. Sci. Upsaliensis, ?er. 4, vol. 5, No. 6, 1922, 

 p. 92. 



Tropiometra afra A. H. Clark, Proc. U. S. Nat. Mus., vol. 34, 1908, p. 315 (description of 7 speci- 

 mens from Sagami Bay); Amer. Nat., vol. 42, 1908, p. 725 (in part; color); Geogr. Joum., 

 Dec. 1908, p. 607 (in part; color); Vid. Medd. Naturh. Foren. K0bonliavn, 1909, p. 124 (speci- 

 men with 93 myzostomcs), p. 185 (near the Goto Is., 36 fms.; Misaki); Crinoids of the Indian 

 Ocean, 1912, p. 176 (Japanese localities). — Gisl]6n, in Th. Mortensen, Hong Kong Nat. Suppl., 

 No. 3, Feb. 1934, p. 6 (Hong Kong), pi. 8 (2 figs.). 



Tropiometra afra var. macrodiscus Gisl^n, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 

 1922, p. 90 (Bock's station 27; notes).— Gisl6n, Zool. Bidrag I'ppsala, vol. 9, 1924, pp. 44, 51, 

 53, 78, 90; fig. 73, p. 75 (syzygial face), fig. 103, p. 89 (syuarthrial face), fig.^. 158, 159, p. 98 

 (articulations of a left Pi) ; Vid. Medd. Dansk Naturh. Foren., vol. 83, 1927, p. 30 (Mortensen'a 

 station 27; notes). 



Tropiometra afra macrodiscus Gisl^n, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 

 1922, p. 5 (Sagami Bay), pp. 7, 91, 93; Zool. Bidrag Uppsala, vol. 9, 1924, pp. 39, 44, 51, 53, 

 78, 90, 275, 278 (Misaki, Japan, 2-3 m., food), p. 285 (Misaki, 0-3 m., detaUs), p. 286; fig. 73, 

 p. 75; fig. 103, p. 87; figs. 158, 159, p. 98; fig. 337, p. 277; fig. 338, p. 281; Joum. Fac. Sci. 

 Imp. Univ. Tokyo, sect. 4, vol. 2, pt. 4, 1931, p. 433 (sparse in the Heliocidaris association). 



Tropiometra encrinus GisLfiN, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 4, 

 (163 m.), p. 6 (Bonin Islands), p. 8, p. 92 (Bocks station 45; detailed notes), p. 182 (listed), 

 figs. 70, 71, p. 88; Zool. Bidrag Uppsala, vol. 9, 1924, p. 41. 



Diagnostic features. — A large stout form with the dorsal surface of the arms 

 smooth, without any trace of a median carination. The cirri are XXIV-L (averag- 

 ing about XXXV), 27^3 (usually about 35), 30-50 (usually about 40) mm. long. 

 The arms are 120-265 (averaging about 200) mm. long. 



This form is more robust and rugged than the preceding {ajra) with somewhat 

 longer and stouter cirri composed of more numerous segments. 



Description. — The centrodorsal is a thick disk with slightly sloping sides. It is 

 up to 12 mm. in diameter at the base with the broad dorsal pole 5-10 (averaging 

 about 7.5) mm. in diameter, flat or slightly concave, sometimes marked with slight, 

 low, and broad radiating ridges or broken hues. The cirrus sockets are arranged in 

 from two to three irregular and crowded marginal rows. 



The cirri are XXIV-L (averaging about XXXV), 27-43 (usually about 35), 

 from 30-50 (usually about 40) mm. long. The cirrus segments are subcqual from 

 one-third again to twice as broad as long. There is usually no opposing spine, but 

 occasionally a slight opposing spine may be present on some of the cirri. The term- 

 inal claw is a little longer than the penultimate segment. The cirri are stout, and 

 usually become somewhat compressed laterally in the distal half. 



The anterolateral angles of the radials are more or less extensively visible in the 

 interradial angles of the calyx. The IBri are oblong, broad, about six times as broad 

 as long, with the lateral borders sharply flattened and closely appressed against those 

 of their neighbors. The IBr2 (axillaries) are broadly pentagonal or almost triangular, 

 about twice as long as the IBri, three times as broad as long. The anterior angle is 

 obtuse, and the lateral edges are straight, sharply flattened, and in close apposition 

 with those of their neighbors. Low synarthrial tubercles are present. 



