A MONOGRAPH OF THE EXISTING CRINOIDS 269 



contrast. The somewhat rigid arms remained curved outward like the petals of a 

 flower, and the old book name "sea-lily" was most appropriate. He subsequently 

 dredged other specimens the coloration of which was so different that they were not 

 even suspected of being the same species. In 1932 he met with Heterometra often, 

 and the diversity of color led to the supposition that he was collecting three different 

 comatulids. 



Dr. Clark says that according to coloration three forms may be recognized, but 

 with sufficient material it is obvious that they intergrade completely. At one extreme 

 are the milk-white forms with rose-colored cirri. When preserved in alcohol or dried 

 these lose much of their beauty, the white becoming dingy or tinged with purple 

 and often small spots or bloches of a purplish shade appear. At the other extreme 

 are the individuals, usually large ones, that are deep red-purple or dark crimson with 

 few or no lighter markings; these commonly have a coarser and more rugged struc- 

 ture than the white ones. The third group includes the more or less handsome indi- 

 viduals with banded arms; these may be white, or at least very light, as to ground 

 color with the arms banded with red or purple of some shade, or they may be red or 

 purple with whitish bands and markings. The number, width, and shade of the arm 

 bands show endless diversity. The cirri are always red or purple of some shade, 

 ranging from light rose to a deep red-violet. One very small specimen with 13 arms 

 about 15 mm. long was very pale brown, the cirri with a very light tinge of violet. 



Abnormal specimens.- In the specimen from Pocock Island one of the IIBr 

 series is 8(3+4; 5 + 6; 7 + 8), one is composed of four elements united in two synar- 

 thrial pairs, and one is 2; of the three IIIBr series one is 1, one is 2, and the third is 

 4(3+4). 



Gislen recorded a specimen from Mjoberg's station 7 with a IIBr series consisting 

 of four ossicles united in two synarthrial pairs and a IIIBr 2(1+2) series. 



In the specimen from Tonkin described by Gislen one of the IBr series is 6(5 + 6). 



In the specimen from Annam an external arm arising from a IIBr 4(3+4) axil- 

 lary has the first syzygy between brachials 4 + 5; another arm on the same postradial 

 series arising from the inner side of a IIIBr 2 axillary has the first syzygy between 

 brachials 7+8; a third arm on the same postradial series arising from the IBr axillary 

 has syzygies between brachials 3+4, 5 + 6, and 7+8. 



Remarks. This species reaches its extreme development (form irregularis) on 

 the coast of Australia, where the individuals are usually large and rugged with nu- 

 merous arms and with the characteristic features of the enlarged proximal pinnules 

 highly developed and often exaggerated. Northward the individuals become less 

 extremely developed and are usually smaller with fewer arms, more slender, and less 

 rugged, with the characteristic features of the proximal pinnules moderately devel- 

 oped. This is the typical form (crenulata) that occurs throughout the range of the 

 other forms, except perhaps in the extreme south, and is the prevailing form at Singa- 

 pore and in the Philippine Islands. From the Aru Islands to the Philippines the 

 species occurs in a still more slender form (aliena, [=aruensis]) in which the cirri are 

 merely slightly carinate distally and the processes on the segments of the enlarged 

 proximal pinnules are only very feebly developed. 



Bell's name decipiens and Carpenter's names bidentata and dubia were applied to 

 young individuals of the highly developed form called irregularis by Bell. 



