326 Mr. F. A. Bather on British Fossil Crinoids. 



Antedon, but as yet undiscovered, is rendered more untenable 

 than ever by the fact that the elaborate researches of Mr. 

 H. Bury (loc. cit.), as well as Barrois, Gotte, and other pre- 

 vious workers, have failed to indicate any traces of it. At 

 the same time the "anal" of Antedon is not the Azygos 

 plate ; for not only does it originate on a level with the radials, 

 but it attains before its disappearance a far higher position 

 than is attained by the Azygos plate in any fossil form. The 

 idea of Messrs. Wachsmuth and Springer, that this plate is 

 absorbed by the other plates, is quite unfounded ; what Dr. 

 W. B. Carpenter * wrote was : — " The entire plate is re- 

 moved at once by a continuance of absorption over its whole 

 surface," not " over the whole surface." The only adequate 

 answer to the question is that given by P. H. Carpenter, viz., 

 that the " anal " of the Pentacrinoid is homologous with the 

 anal x in the adult Palaeozoic Fistulata. The positions 

 which it successively assumes can, as we shall see, only be 

 explained on this hypothesis. To this answer I only see one 

 objection ; namely, that Antedon and the Fistulata have 

 always been placed by both Wachsmuth and Springer and 

 P. H. Carpenter in different " independent primary divisions " 

 of the Crinoidea, and still are so placed t- But with this 

 objection 1 must leave Dr. Carpenter himself to deal. 



Secondly, whether this homology be granted or not, what 

 light, on the assumption that ontogeny reproduces phylogeny, 

 can a recent Antedon possibly throw on the ancestral condi- 

 tions of Silurian Fistulata ? Let us overlook the objection 

 just mentioned, and let us suppose that Antedon is, after all, 

 lineally descended from the Fistulata through either Agassiz- 

 ocrinus or the later Poteriocrinidaj — even then what does it 

 tell us ? It merely passes through the stages that are repre- 

 sented in the paleeontological (*. e. the phylogenetic) series by 

 Ceriocrinus, Erisocrtnus, and Stemmatocrinus. In fact it 

 hardly takes us back to the middle of the Carboniferous, cer- 

 tainly not to the Ordovician and Silurian genera. Conse- 

 quently Dr. Carpenter's conclusion that " Cyathocrinus, or a 

 Dendrocrinoid form with the two halves of the compound 

 radial united, is a lower type than Iocrinus " falls to the 

 ground. Under any circumstances his argument would prove 

 Ceriocrinus and Graphiocrinus earlier than Zeocrinus or even 

 Heterocrrnus — a sufficient reductio ad absurdum. 



* " Researches on the structure &c. of Antedon &c." Phil. Trans, 

 vol. clvi. p. 747, London, 1860. 



f P. H. C. in Nicholson and Lvdeliker's ' Manual of Palaeontology,' 

 i. p. 445, 1800. 



