A MONOGRAPH OF THE EXISTING CRINOIDS 147 



posed the name Eudiocrinus. Carpenter noted that "in its central mouth and in the 

 structure of the calyx Eudiocrinus is essentially an Antedon. But the sacculi which are 

 usually so abundant at the sides of the ambulacra of this genus are not so constant in 

 Eudiocrinus. E. indivisus has numbers of them, while they are scanty in E. varians, 

 and altogether absent in the two remaining species [semperi and japonicus], which I 

 have never found to be the case in Antedon, though I have examined over one hundred 

 species of this genus." He noted that in E. indivisus the sacculi are "tolerably close 

 on the arms, but larger and more closely set at the sides of the pinnule-ambulacra, 

 which have only the very slightest trace of any superficial limestone deposits." 



In 1884 in his report upon the stalked crinoids collected by the Challenger, Car- 

 penter discussed Eudiocrinus at considerable length. He remarked that in E. in- 

 divisus the two ossicles following the radials are united by syzygy, and the epizygal of 

 this syzygial pair bears a pinnule "which clearly shows that they must be considered as 

 arm-joints and not as belonging to the calyx, although they undoubtedly represent the 

 so-called second and third radials [the ossicles of the IBr series] of a ten-armed Cri- 

 noid." He said further that in the other species of Eudiocrinus — that is, in the 

 species now assigned to Pentametrocrinus — these primitively separate ossicles are not 

 united by syzygy but are articulated, just as in Thaumatocrinus [= the young of 

 Decametrocrinus]. The second one bears a pinnule both in Thaumatocrinus and in 

 Eudiocrinus [Pentametrocrinus] varians; but in Eudiocrinus [Pentametrocrinus] semperi 

 and in E. [P.] japonicus the first pinnule is on the fourth ossicle after the radial. He 

 said that this would correspond to the second brachial of a 10-anned crinoid, but it is 

 really the fourth brachial in Eudiocrinus. Lastly, he remarked, in Perrier's Eudio- 

 crinus atlanticus the first pinnule is on the fifth brachial, which corresponds to the 

 third brachial of an Antedon. 



In the Challenger report on the comatulids published in 1888 Carpenter gave no 

 new information regarding E. indivisus. His account of the genus Eudiocrinus is 

 based almost wholly upon the three species of Pentametrocrinus secured by the Chal- 

 lenger and the one (atlanticus) described by Perrier. His description of the disk and 

 of the articular faces of the radials is entirely based upon the Challenger species of 

 Pentametrocrinus. 



In 1894 Prof. F. Jeffrey Bell described and figured a second species of Eudiocrinus 

 from the Macclesfield Bank, which was closely related to E. indivisus. In fact Bell's 

 new species, E. granulatus, subsequently proved to be a synonym of E. indivisus. 



In 1908, having obtained from southern Japan a single specimen of a new species, 

 which I described as Eudiocrinus variegatus, I showed that whereas in E. indivisus 

 and its close relatives the two ossicles united by syzygy immediately following the 

 radials are the equivalent of the IBr series in comatulids with 10 or more arms (as 

 was suggested by Carpenter in 1884) there are no representatives of the IBr series at 

 all in Eudiocrinus varians, E. japonicus, E. semperi, E. atlanticus, or E. tuberculatus. 

 These last I therefore removed from the genus Eudiocrinus, placing them in the new 

 genus Pentametrocrinus. At the same time I showed that Eudiocrinus, as restricted 

 by the removal of various species to Pentametrocrinus, is most closely related to 

 Zygometra, and I united Eudiocrinus and Zygometra in the new family Zygometridae. 

 In another paper published in 1908 I described Eudiocrinus serripinna, which 

 had been dredged by the Albatross at station 5136 in the Philippines, and in 1909 I 



