A MONOGRAPH OF THE EXISTING CRINOIDS 101 



October 24, 1913 [H. L. Clark, 1915, 1921; A. H. Clark, 1918, 1929] (7, M.C.Z., 595). 



Mer, Murray Islands, Torres Strait; H. L.' Clark, October 1913 [H. L. Clark, 

 1915, 1921; A. H. Clark, 1918, 1929] (3, M.C.Z.," 552 [cotype], 596, 598). 



Magneto, station XIX; about one-half mile north of Eagle Island, Great Barrier 

 reef; 18 meters; shell gravel; rich Halimeda; March 10, 1929 (1). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; Amboina Bay; about 

 100-130 meters; stones; February 25, 1922 (1, C.M.). 



Geographical range. From Torres Strait to Amboina. 



Bathymetrical range. From the shore line down to 100 (7130) meters. 



Occurrence. Dr. Hubert Lyman Clark said that, except for the species of Co- 

 masteridae, this was the commonest crinoid at Mer, Murray Islands; but it was not 

 really common, since he found only 12 individuals in five weeks of diligent search. 

 It was not infrequently met with near the outer margin of the southwestern reef 

 flat, but unfortunately it was not common enough to permit of any extended observa- 

 tions on its habits and reactions. It was not ordinarily at all active, but clung very 

 tenaciously to the fragment of rock or coral to which its cirri attached it. The cirri 

 are notably strong, and it was frequently no easy task to detach them. 



History. This species was first described under the name Oligometra anisa by 

 Dr. Hubert Lyman Clark hi 1915. He remarked that although it is no doubt related 

 to 0. carpenteri this species is readily distinguished by the more numerous cirri with 

 fewer segments, by the shorter arms with about half as many brachials, and the utterly 

 different lower pinnules. 



In my report upon the unstalked crinoids of the Siboga expedition published in 

 1918 I included Oligometra anisa in the synonymy of Oligometrides adeonae without 

 comment. 



In 1921 Dr. H. L. Clark wrote that the great diversity in color shown by this 

 species led him to suppose that he had found several species of 10-armed colobometrids 

 at Mer, but critical study in Cambridge brought him to the conclusion that all the 

 individuals represent a single species. He remarked that hi spite of his somewhat 

 detailed description of the pinnules I put anisa in the synonymy of Oligometrides 

 adeonae, whereas it is evidently an Oligometra, and even after an examination of 

 the holotype and all the other specimens he had insisted that they represent adeonae. 

 He said that I had lent him specimens of adeonae from the Aru Islands [Siboga station 

 273] which he had compared carefully with the Murray Island material. There was 

 no doubt in his mind that the two species are quite distinct; the cirrus segments have 

 conspicuous transverse ridges hi adeonae which are wanting (or at most very faint) 

 hi anisa, while the difference hi the lower pinnules is even more marked. In adeonae 

 Pj is the largest, P 2 is slightly smaller, P 3 is still smaller, and P 4 is still smaller, but 

 similar. In anisa PI is smaller than P 2 , which is much larger and with more seg- 

 ments than in adeonae; P 3 is about as large as P, or a little smaller; P 4 is abruptly 

 smaller than P 3 and quite different in form. In adeonae the lower pinnules tend to 

 be prismatic, while in anisa they are more terete. In some of the specimens of anisa 

 certain of the lower pinnules have been broken off and are regenerating, a condition 

 which is quite deceptive at first sight. There is also some diversity hi the size and 

 proportions of the lower pinnules which is probably due hi large part to differences hi 

 age. Dr. Clark remarked that the characteristic features of this species are, however, 



