128 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



two sharp points near the middle of the distal edge. The lower part of the muscular 

 fossae is occupied by two or three strongly marked ridges with intervening furrows 

 which are altogether absent in less mature individuals. The latter, however, have the 

 upper end of the muscle plates more everted than in the adults, so that the central 

 opening of the calyx is relatively larger and more pentagonal in appearance. 



Carpenter had no doubt that these were merely differences of growth, and that they 

 are not of specific value as he had supposed when the plates were lettered. On plate 



3 of the Challenger report a young individual, the centrodorsal and radial pentagon of 

 which are shown in figures 5, a-c, is called eversa, and a full grown one, details of which 

 are shown in figures 4, a-c, is called radiospina. In the explanation to the plate figures 



4 and 5 are both given under the name breviradia. 



It is possible that two species are confused under the name breviradia. The 

 description is applicable to the form referred to by Carpenter as the older and called 

 on plate 3 radiospina, which therefore becomes a synonym of breviradia. If the younger 

 form should prove to be distinct the name eversa, occurring on plate 3, is available for it. 



Localities. Challenger station 170A; near the Kermadec Islands (lat. 2945' S., 

 long. 17811' W.); 1,152 meters; bottom temperature 4.17 C.; volcanic mud; July 14, 

 1874 [von Graff, 1883, 1884, 1885; P. H. Carpenter, 1888; Walther, 1894; Hartlaub, 

 1895; Hutton, 1904; A. H. Clark, 1907, 1909, 1912, 1913, 1918] (3, B. M.). 



Challenger station 175; near Kandavu, Fiji (lat. 1902' S., long. 17710' E.); 

 2,285 meters; bottom temperature 2.2 C.; globigerina ooze; August 12, 1874 [P. H. 

 Carpenter, 1888; Walther, 1894; Hartlaub, 1895; Hutton, 1904; A. H. Clark, 1907, 

 1909, 1912, 1913, 1918] (1, B. M.). 



Geographical range. From Fiji southward to the Kermadec Islands northeast of 

 New Zealand. 



Bathymetrical range. From 1,152 to 2,285 meters. 



Thermal range From 2.2 to 4.17 C. 



History. This species was first mentioned by Prof. Ludwig von Graff who in 

 1883 recorded and described the myzostomes found with the specimens from Challenger 

 station 170; in recording the host of these myzostomes Professor von Graff used the 

 name Antedon radiospina. He used this name again in 1884 and in 1885. When I 

 saw him at Graz in 1910 he told me that for the hosts of myzostomes he had accepted 

 the names given him by Carpenter and had left to Carpenter the task of allocating the 

 names in the synonymy. In the Challenger reports on the comatulids published in 

 1888 Carpenter gave a detailed account of this species under the name Antedon 

 breviradia, in the text making no mention of any other names. In the explanation of 

 the figures on plate 3 he listed figures 4 and 5 under Antedon breviradia, but at the bottom 

 of the plate the species illustrated by figure 4 is given as Antedon radiospina, and that 

 illustrated by figure 5 as Antedon eversa. 



Walther in 1894, Hartlaub in 1895, and Hutton in 1904 mentioned Antedon 

 breviradia, taking their information from the Challenger report. 



In my first revision of the genus Antedon published in 1907 breviradia was referred 

 to the new genus Thalassometra, and in 1909 I referred it to the new genus Stiremetra. 

 In 1912 I listed it, with the synonymy and range, in my memoir on the crinoids of the 

 Indian Ocean. In my paper on the crinoids of the British Museum published in 1913 

 I mentioned having seen four specimens from Challenger stations 175 and 170a, and 



