PART 5 A MONOGRAPH OF THE EXISTING CRIXOIDS 109 



The color in alcohol is brownish yello\v. 



Locality. Unknown [A. H. Clark, 1908, 1909, 1912, 1918] (1, C.M.). 



MASTIGOMETRA MICROPODA A. H. Clark 



FIGURE 8 

 [See also vol. 1, pt. 2, figs. 570, 571, p. 298] 



Mastigometra micropoda A. H. CLARK, Proc. U.S. Nat. Mus., vol. 36, 1909, p. 649 (description; ?India) ; 

 Vid. Medd. Nat. Foren. K0benhavn, 1909, p. 128 (closely related to M. flagellifera and to the 

 species of Anledon; Indian Ocean and Ceylon); Crinoids of the Indian Ocean, 1912, p. 227 (de- 

 tailed description; ?India; Ceylon); fig. 42, p. 228. H. I,. CLARK, Spolia Zeylanica, vol. 10, pt. 

 37, 1915, p. 93 (occurs at Ceylon). A. H. CLARK, Unstalked crinoids of the Siboja-Exped., 1918, 

 p. 198 (in key; range), p. 200 (references). 



Diagnostic features. The L-XC cirri have about 16 segments, of which the sixth 

 and following are about as long as broad; P, is 15 mm. and P 2 is 9 mm. long. 



The arms are about SO mm. and the cirri about 10 mm. in length in the holot3 r pe. 



Description. The centrodorsal is low hemispherical, 4 mm. in diameter at the 

 base, the polar area slightly convex, or flattened; the cirrus sockets are very numerous 

 and are arranged in four or five closely crowded alternating rows. 



Cirri L-XC, 16, about 10 mm. long; the first two segments are short, rather over 

 twice as broad as long, the third is from as long as broad to a third again as long as 

 broad, and the fourth and fifth are slightly longer; the following segments are subequal, 

 about as long as broad; the third to sixth segments are slightly constricted centrally, 

 the remaining segments having the ventral surface practically straight and the 

 dorsal with a slight median concavity. The cirri become somewhat compressed laterally 

 in the distal two thirds and therefore appear very slightly broader in lateral view. The 

 opposing spine is represented by a slight terminally situated tubercle which may be 

 obsolete. 



Scattered calcareous granules are present along the ambulacral grooves of the disk 

 and perisomic interradials may be present between the IBr! as in Antedon bifida. 



The distal borders of the radials are even with the edge of the centrodorsal. The 

 IBr[ are very short, five or six tunes as broad as long, of uniform height, not quite in 

 apposition basally, the lateral edges of adjacent plates diverging distally. The IBr 2 

 are triangular, about half again as broad as long, the distal angle somewhat produced, 

 the proximal border as long as the proximal border of the IBr^ 



The 10 arms are probably about 80 mm. long, and resemble in structure those of 

 M. flagettifera. 



The distal intersyzygial interval is 3 muscular articulations. 



P, is 15 mm. long, much stouter basally than the succeeding, though tapering 

 evenly to an exceedingly slender and delicate flagellate tip. P 2 is 9 mm. long. The 

 following pinnules gradually decrease in length. The pinnules are of the same pro- 

 portions and structure as are those of M. flagettifera,. 



The color in alcohol is brownish white. 



Localities. ?India [A. H. Clark, 1909, 1912, 1918] (4, U.S.N.M., 35655 [1711], 

 35656 [16H]; the holotype, I.M.). Type locality. 



Off the Colombo Light House, Ceylon; 48 meters [A. H. Clark, 1909, 1912, 1918] 

 (1,I.M.). 



Remarks. The five known specimens of this species were all collected by the 

 Investigator; oi\\j one of them bears a definite locality. 



