528 



BULLETIN 82, UNITED STATES NATIONAL MUSEXIM VOLUME l 



2mnn 



Figure 27. — Psathyromelra anomala A. H. Clark, holotype: a. Radial view; b, centro- 

 dorsal from the other side; c, proximal part of P2; d, part of genital pinnule beyond 

 gonad. 



PSATHYROMETKA GRACILLIMA A. H. Clark 



FionRE 28 



[See also vol. 1, pt. 2, figs. 578, 579, p. 298] 



Psaihyrometra graciUima A. H. Clark, Proc. Biol. See. Washington, vol. 22, 1909, p. 149 (description; 

 19''35' N., 92°24' E.; 272 fms.) ; Crinoids of the Indian Ocean, 1912, p. 21 (intermediate between 

 Psathyromelra and Leplometra) , p. 236 (synonymy; detailed description; locality), fig. 44, p. 237; 

 Die CrinoJden der Antarktis, 1915, p. 116 (range); Unstalked crinoids of the .St'boi/a-Exped., 

 1918, pp. 225, 226 (in key; range), p. 228 (references). 



Diagnostic features. — The centrodorsal is sharply conical but much wider at the 

 base than it is high, the ratio being about 1.8:1 ; the bare interradial areas are usuallj' 

 much wider than the individual peripheral sockets and are grooved; the sockets lie 

 fairly dose together in each radial area and are arranged in two (apically) to four 

 (peripherally) more or less regular columns; the arms are rather slender in the holotype, 

 the ratio of the length of the division series plus the first nine brachials to the 

 width of the first syzygy being 7.33:1 as opposed to about 6.7:1 in the two specimens 

 of Ps. mira measured; the cirri probably taper evenly like those of mira with the 

 terminal segments elongate. 



Description. — The centrodorsal is sharply conical, 4 mm. broad at the base and 

 2.5 mm. high, its sides divided into 5 radial areas by 5 interradial furrows which are 

 somewhat broader than the adjacent cirrus sockets. There are from 8 to 10 well- 

 separated cirrus sockets in each radial area which are arranged appro.ximatcly in 4 

 more or less irregular colimins. 



The cirri are XIj-L, about 25, long, slender, smooth and delicate. 



