A MONOGRAPH OF THE EXISTING CRINOIDS 213 



Himerometra persica A. H. CLARK, Smithsonian Misc. Coll., vol. 50, 1907, p. 356 (listed; nomen 

 nudum); Bull. Mus. Comp. Zool., vol. 51, 1908, p. 243 (description; Persian Gulf); Proc. Biol. 

 Soc. Washington, vol. 22, 1909, p. 7 (listed); Amer. Nat., vol. 43, 1909, p. 256 (absent from the 

 Red Sea; Persian Gulf to Philippines [specimens from last really H. bartschi]); Crinoids of the 

 Indian Ocean, 1912, p. 11 (occurs both east and west of Ceylon), p. 21 (range covers that of all 

 the other species, and extends farther west), p. 116 (synonymy; range [specimens from the 

 Philippines are H. bartschi]); Proc. U. S. Nat. Mus., vol. 46, 1913, p. 285 (in key), p. 289 (anno- 

 tated synonymy; range); Unstalked crinoids of the Siboga-Exped., 1918, p. 73 (in key; range). 

 GISL^N, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, pp. 22, 23, 46, 48, 

 49, 52. A. H. CLARK, John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1936, p. 99 

 (range), p. 103. 



Diagnostic features. The proximal pinnules are slender, flagellate distally, and very 

 long, composed of perfectly smooth segments most or all of which are longer than 

 broad, with a few of the earlier narrowly but prominently carinate; the earlier seg- 

 ments of the following pinnules are very strongly carinate. The cirri have 35 segments 

 of which those in the outer half have prominent dorsal spines. The 20-25 arms are 

 about 150 mm. long. 



Description. The centrodorsal is low hemispherical with a large bare polar area. 

 The cirri are about XXV, 35, 27 mm. long. Most of the cirrus segments are slightly 

 longer than broad, the distal about as long as broad; the last 16-18 bear sharp dorsal 

 spines. 



The radials are just visible beyond the rim of the centrodorsal. The IBr, are 

 trapezoidal, about three times as broad as long. The IBr 2 (axillaries) are pentagonal, 

 about half again as broad as long, with a sharp distal angle. The IIBr series are 

 4(3+4) or 2. The division series are strongly rounded dorsally and widely free 

 laterally. 



The 20-25 arms are 150 mm. in length. The first eight brachials are roughly 

 oblong, those following becoming wedge-shaped, much broader than long, and oblong 

 toward the end of the arms. 



Syzygies occur between brachials 3+4, again in the vicinity of the seventeenth 

 brachial, and distally at intervals of 6 to 13 (usually about 8) muscular articulations. 



P D is 13 mm. long, very slender and flagellate, with 36 segments, all of which are 

 somewhat longer than broad, but not much so; the first four segments are the broadest 

 and are slightly carinate. PI is similar but longer, 16 mm. in length, and stouter 

 basally; the five or six basal segments are sharply carinate, and from this point the 

 pinnule tapers gradually to the long and delicate flagellate tip. P 2 resembles Pj and 

 is of the same length. The next few pinnules decrease rapidly in length, and those 

 following increase somewhat distally, but do not become very long. The carmatiou 

 of the basal pinnule segments becomes less and less merked distally and is not notice- 

 able after P 6 ; it is at its maximum on PI and P 2 . 



The color in alcohol is dull brown, the skeleton somewhat lighter. 



Locality. Persian Gulf; F. W. Townsend [A. H. Clark, 1908] (2, M.C.Z., 291). 



Remarks. This species is as yet known only from the two specimens described 

 in 1908. It is very distinct from all the others in the genus with the exception of 

 H. bartschi, which will probably prove to be simply its Malayan variety. 



