A MONOGRAPH OF THE EXISTING CRINOIDS 287 



Siboga station 99; anchorage off North Ubian, southern part of the Jolo (Sulu) 

 Archipelago (hit. 607'30" N., long. 12026'00" E.); 16-23 meters; lithothamnion 

 bottom; July 28-30, 1899 [A. H. Clark, 1918] (1, Amsterdam Mus.). 



Singapore; shallow water; Mr. Svend Gad (3, U. S. N. M., E. 1082; C. M.). 



Amboina; Dr. J. Brock [Hartlaub, 1890, 1891; A. H. Clark, 1907, 1909, 1912). 



Geographical range. From the Philippines to Singapore and southward to 

 Amboina. 



Bathymetrical range. From the shoreline down to 36 (?55) meters. 



History. This species was first described under the name of Antedon affinis by 

 Dr. Clemens Hartlaub in 1890, and was redescribed and figured by him in the following 

 year. He remarked that this new species shows much similarity to Antedon biparti- 

 pinna P. H. Carpenter and A. ludovici P. H. Carpenter apparently representatives 

 of the same species which are also forms combining the presence of IIIBr series with 

 slender carinate pinnules in the proximal arm region. As his specimen was not sexually 

 mature Hartlaub said it was not impossible that the new species may prove to be 

 simply a young stage of Antedon ludovici, although to him the characteristic features 

 seem to point more to specific distinctness. He said that Antedon affinis differs from 

 A. ludovici in its much smaller size and in its very slender build. In addition, its 

 cirri have a relatively much finer structure and a smaller number of segments. Also, 

 the synarthrial tubercles so characteristic of A. ludovici are lacking and the general 

 surface of the first eight or nine brachials has only a suggestion of the unevenness 

 which we find so marked in that species. Lastly the triangular brachials that follow 

 the proximal brachials are markedly longer in Antedon affinis than the corresponding 

 brachials in A. ludovici, which also are not triangular. The agreement between the 

 two forms, according to Dr. Hartlaub, lies in the carination of the proximal pinnules 

 and in the form of the proximal brachials, especially that of the first syzygial pair, 

 and finally in the arrangement of the arms and the manner of the division of the post- 

 radial series. 



In my first revision of the genus Antedon published in 1907 this species was 

 assigned to the new genus Himerometra, and hi the revision of the family Himero- 

 metridae published in 1909 it was assigned to the new genus Heterometra. 



In 1918 a specimen from Siboga station 99 was recorded and notes on it were given. 



HETEROMETRA PULCHRA A. H. Clark 



PLATE 36, FIGURES 164, 165 



Helerometra pulchra A. H. CLAKK, Rec. Indian Mus., vol. 7, pt. 3, No. 26, July 1912, p. 269 (nomen 

 nudum; Arrakan coast) ; Crinoids of the Indian Ocean, November 1912, p. 317 (detailed descrip- 

 tion; localities; comparisons); Unstalked crinoids of the Si&o^a-Exped., 1918, p. 78 (in key; 

 range); Treubia, vol. 14, livr. 2, 1933, p. 208 (not included in Siboga collection), p. 212 (near 

 Deli). GISLEN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, p. 22. 



Diagnostic features. The brachials are distinctly wedge-shaped with the ends 

 never quite parallel and are not exceedingly short. The enlarged lower pinnules are 

 smooth, with the earlier segments keeled. The cirri are 25-35 mm. long with 32-15 

 segments of which the longest are slightly longer than broad and the outer are slightly 

 broader than long and bear rather small, though sharp and prominent, dorsal spines. 

 The 24-32 arms are 85+ mm. long. P 3 is the largest and longest pinnule, 14-22 mm. 

 long with 22-25 segments. 



