PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 317 



The specimens included under the name rhomboidea, from Albatross stas. 3357 

 and 3424, he had at first considered as representing a new species. He gave a detailed 

 description of them, based upon the single individual from sta. 3357, except for the 

 cirri and pinnules which were described from the specimen from sta. 3424. This new 

 species seemed to him to differ from P. H. Carpenter's description and figure of rhom- 

 boidea in several particulars. In Carpenter's figure the centrodorsal is bounded ven- 

 trally by a sharp and straight line; only the interradial angles of the radials are visible; 

 and the IBr t seem to be in lateral contact and are, like the first brachials, "deeply 

 incised." In all these details rhomboidea as described by Carpenter differed from his 

 specimens, and therefore the latter seemed to him to deserve specific separation. 



Later, however, he was able to study a specimen of rhomboidea in the Hamburg 

 museum which had been collected by Dr. Rehberg in Smyth's Channel, and he then 

 came to the conclusion that the apparent differences were due merely to the insuffi- 

 ciencies of Carpenter's figure. The Hamburg specimen agreed in every respect with 

 those collected by the Albatross; he decided, therefore, that this species, rhomboidea, 

 occurs on the Pacific coast of Central America as well as in the Magellanic region. 



The individuals from the Tres Marias Islands differed more or less from that 

 from sta. 3357, possibly, he remarked, because of the very different depth of the 

 habitat. The former ha\e a much more slender habitus, the synarthrial tubercles 

 are only feebly developed while the articular tubercles are entirely lacking, and the 

 brachials, especially the syzygial pairs, are more elongate. 



Antedon tanneri from sta. 3385, which he described in detail, he said possesses 

 an entirely different habitus from the form he called rhomboidea, and especially the 

 strong serration of the profile of the arms is noteworthy. He described minutely 

 the differences in the radial articular faces which he considered as especially significant. 

 But none of the differences between the description of the specimens referred to rhom- 

 boidea and that of tanneri in the light of our present knowledge of the variability of 

 the species of Florometra seem sufficient to warrant specific separation. 



In 1908 I recorded as rhomboidea specimens from three additional Albatross stations 

 4621, 4622 and 4630, off the western coast of Central America obtained by the Albatross 

 expedition to the eastern tropical Pacific from October 1904, to March 1905, under the 

 direction of Mr. Agassiz. The specimens appeared to be practically identical with 

 those described as rhomboidea by Hartlaub, but I had no representatives of true rhom- 

 boidea for comparison, nor any of those described by him under that name 



In a discussion of the species of this genus published in 1915, the specimens recorded 

 by Hartlaub and by myself as rhomboidea were mentioned under the name of Pro- 

 machocrinus (Florometra) magellanica, it having been found that rhomboidea is a 

 synonym of magellanica; tanneri was maintained as a distinct species. 



In a revision of the genus Florometra incorporated in the Siboga report in 1918, 

 writ ton after the examination of all the available material, including numerous 

 examples of the Magellanic species in the museums of London, Paris and Hamburg, I 

 considered magellanica (including rhomboidea) as a distinct species confined to southern 

 South America; tanneri I admitted as a good species giving its range from southern 

 California to Panama Bay in 102 to 711 meters, the extension resulting from the 

 identification with it of some small specimens from southern California in the U.S. 

 National Museum collection; and the individuals recorded as rhomboidea by Hartlaub 

 and by myself I placed in the synonymy of perplexa. But I remarked that while 



