194 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The radials project very slightly beyond the rim of the centrodorsal ; their antero- 

 lateral angles are slightly separated so that the bases of adjacent IBrj are not in 

 contact. The IBri are short, oblong, nearly 4 times as broad as long, with a low, 

 though distinct, broad rounded median carination. The IBra (axillaries) are broadly 

 pentagonal, half again as broad as long, their lateral edges as long as those of the IBr, 

 and makmg with them a broadly obtuse angle; in their proximal two-thirds they bear 

 a broad rounded median carination similar to that on the IBri. 



The 10 arms are about 35 mm. long. The proximal oblong brachials have a 

 slight trace of a rounded median carination. 



Pi is 4.5 mm. long, evenly tapering to a delicate tip, somewhat stiffened, rounded 

 prismatic, with 13 segments of which the first 2 are short, the third is slightly longer 

 than broad, the fourth is half again as long as broad, and those following slowly 

 increase in length so that the distal are about twice as long as broad. Beginning on 

 the third segment very small but very sharp spines are developed on the distal ventral 

 angles and in the middorsal portion of each segment. P2 is 6 mm. long with 12 or 13 

 segments, resembling Pj but larger, stouter, and stiffer with slightly longer spines at 

 the distal prismatic angles of the segments. P3 is 3 mm. long, more slender than P, 

 though essentially similar to it but without the spines on the distal edges of the seg- 

 ments; it is slightly stiffened. P4 and the following pinnules are slightly shorter than 

 P3, and apparently are not stiffened, at least distally. The distal pinnules are slender, 

 5 mm. long with 15 much elongated segments. 



Localities. — Investigator; ?India (probably Ceylon) [A. H. Clark, 1912, 1918] 

 (1,I.M.). 



Investigator; ?Tndia (probably Ceylon) [A. H. Clark, 1912] (1, 1. M.). 



Investigator; 1 mile east of the Terribles, a line of rocks from 10 to 12 miles west 

 of the west point of Kamree Island, on the coast of Arrakan, Burma (lat. 19°27' N., 

 long 93°1S' E.); 24 meters (1, U. S. N. M., 35370). 



Geographical range. — Definitely known only from the Arrakan coast of Burma; 

 probably also occurs at Ceylon. 



Bathymetrical range. — The only definite record is 24 meters. 



History. — This species was first recorded under the name Prometra brevicirra 

 {nomen nudum) on the basis of a specimen from ?India in a paper by me on a small 

 collection of crinoids from the Indian Ocean which was published in July 1912. It 

 was first described under the name Colobometra (Prometra) bremcirra from another 

 specimen from ?India in an appendix to my memoir on the crinoids of the Indian 

 Ocean published on November 22, 1912. 



In the original description it was said to be most closely related to C. (P.) chad- 

 wicki, with which it agrees in the relative proportions of its lower pinnules, though 

 these are as a whole much shorter. It is a smaller form than chaduncki with propor- 

 tionately shorter cirri which are composed of much shorter segments. Pj is much less 

 elongate than the same pinnule in chadwicki, and is more slender with fewer segments 

 which do not become so elongate distaUy. In C. (P.) brevicirra the cirri, though short, 

 are one-third again as long as P2, whereas in C. (P.) chadwicki P2 and the cirri are of 

 about the same length. In my report upon the unstalked crinoids of the Siboga 

 expedition published iu 1918 I included brevicirra in the key to the species of Decametra, 

 giving as the habitat Ceylon and vicinity. 



