VIII. Ci/athocn'nu^. 205 



sidered as a s>monym of C phmu-t. There is therefore no 

 difficulty in deciding what Miller meant by C. planus, and 

 there should consequently be no ditficulry in distinguishing 

 the genus Cf/atJiocnntts. 



Before leaving C. pfantis, however, it may b3 as well to 

 correct a few mistakes made by the earlier writers, lest they 

 should again prove cause of confusion. 



Miller's erroneous ascription of cirri to the species has 

 already been noted. With regard to the arms Miller wrote 

 (p. 87), **they are all tentaculated at alternate sides, and 

 resemble those of Pentacrinus Caput Medus»." Similarly 

 the Austins, though they scouted Miller's tigure of the arras, 

 remarked (p. 60), "The rays were no doubt tentaculated, 

 although none of the specimens show the tentacula." It is 

 certain, however, that tentacula or pinnules are not present 

 in this species. 



The Ashraolean specimen figured by Miller showed the base 

 of the anal tube cle^irly ; Miller, however, merely said (p. 87), 

 " this [abdominal] integument is swollen out, and gives the 

 specimen a singular appearance." The Austins regarded 

 tins aperture as the mouth. De Kouinck and Le Hon* 

 appear to have understood that it was connected with the 

 anus ; but neither they nor previous writers were aware that 

 the opening was followed by an anal tube. The plates 

 around the base of this tube were displayed by Miller in his 

 dissected diagram, fig. 30. Wachsrauth and Springer, how- 

 ever (Rev. I. 81. footnote 1) consider that "the four small 

 plates, arranged in the figure in a half circle, are to represent 

 the interradials (oral plates) [deltoids] in the dome, and not 

 the plates of the ventral sac, as might be expected." This 

 cannot be right : the specimen, as proved by fig. 29, possessed 

 no deltoids, while in both figures the letter T points to a 

 larger and irregularly shaped plate which was most probably 

 the madreporite. 



Miller distinctly (p. 87), and the Austins in more ambiguous 

 language (p. 59), both stated that the articular facet of the 

 radial was perforated. To the question whether there are 

 any species of Ci/athocrtnus that possess this character we 

 shall recur later on ; in the Carboniferous species C. plamts, 

 at any rate, there is no doubt that in the radial facet the 

 axial canal is not separated from the ventral groove. 



• * Recherolie^ sur le^ Crmoides du Terrain Carbonif ere de la Belgique/ 

 M^m. Acad. Rot. Belgique, vol. xsviii. p. 81 : Brussels. 1854. 



Ann. lC- J/ty. X Hii-f. Ser. t3. Vol. ix. 15 



