PAET 5 A MONOGRAPH OF THE EXISTING CRINOIDS 323 



Thermal range.— From 1.44° C. to 6.78° C; the average of 14 records is 3.18° C. 



History. — During the Albatross cruise of 1906 I collected 28 specimens of this 

 species, 14 off Attu Island in the Aleutians (sta. 4784) and 14 in Yezo Strait (stas. 

 5032 and 5033). Their brilliant yellow color and large size made them very conspicuous 

 objects in the net, especially those taken in Yezo Strait which were considerably larger 

 than those from Attu. 



On commencing the intensive study of the crinoids after my return, I found in the 

 U.S. National Museum no less than 659 specimens belonging to this species which had 

 been accumulating as a result of the investigations of the Albatross in Alaskan waters. 

 The species had first been discovered on August 9, 1888 (sta. 2853); most of the speci- 

 mens had been collected during the summer of 1890. 



In a preliminary paper published on September 17, 1907, I described as new 

 Antedon asperrima, based upon some remarkably fine individuals from sta. 3332; 

 A. inexpectata, based on specimens from sta. 2853; and A. rathbuni, based upon speci- 

 mens which I had collected at sta. 5033 in Yezo Strait the preceding year and which 

 still retained their bright yellow color. Marked differences in the proportions of the 

 lower pinnules were supposed to separate asperrima from the other two forms, which 

 were separated from each other on the basis of the number of cirrus segments, the 

 shape of the brachials, and the greater or lesser development of articular tubercles. 



These three nominal species were removed to the new genus Heliometra on its 

 establishment later in 1907. 



Among the collections of the Copenhagen Museum sent me for study I found a 

 curious individual labeled as doubtfully from Tsugaru Strait which I took to be a 

 specimen of a varietal form of Heliometra glacialis with the distal intersyzygial interval 

 of 3 instead of the usual 4 muscidar articulations; this I described in 1908 under the 

 name of Heliometra glacialis biarticulata. In 1909 I again mentioned it, together with 

 another similar one in the collection of the U.S. National Museum which had been 

 purchased at Shanghai. On reexamination I find that the latter is identical with 

 rathbuni from Yezo Strait, which is the same as asperrima. The former was returned 

 to Copenhagen, but I have no doubt that it, too, is a specimen of asperrima which may 

 well occur in the Tsugaru Strait. 



In 1915 asperrima, inexpectata and rathbuni were removed to the new genus 

 Florometra. 



Diuing the preparation of the Siboga report (1918) I again went over all the 

 available specimens of the species of Florometra in the light of about ten years' addi- 

 tional experience with other forms, especially with Heliometra glacialis. It was now 

 evident that inexpectata, in spite of the very different pinnulation, is a sj-nonym of 

 asperrima, and also that the specimens called rathbuni from Yezo Strait are very 

 closely related to it, if not identical with it. These last, however, I united with the 

 more southern laodice which I am now convinced is a synonym of mariae, while rathbuni 

 is a sj'nonym of asperrima. 



In a memoir on the crinoids of the Okhotsk and Japanese seas published in 1937, 

 this species was revised, and Antedon rathbuni, A. inexpectata and Heliometra glacialis 

 biarticulata were included under asperrima as synonyms. Several new localities were 

 given, with notes on the specimens from each. A complete list of previous localities 

 was included, and the geographical, bathymetrical and thermal ranges were given, 

 together with a general accoimt of its associations. 



