Dr. F. A. Bather — On Edrioasteroidea. 543 



HE. — Studies ik Edrioasteroidea.^ III. Leretodisgus, N".a. eor 

 Agelaceinites Dicksoni, Billin-gs. 



By F. A. Bather, M.A., D.Sc, Brit. Mus. (Nat. Hist.). 



(PLATE XXY.) 



Previous History. 



rPHE specimen herein to be considered is one of great historical 

 JL interest, for it was the first specimen of an Edrioasteroid made 

 known to science. It was discovered by Dr. J. J. Bigsby in limestone 

 now recognised as of Lower Trenton age, forming Table Rock at the 

 Chaudiere Falls on the Ottawa River at Ottawa (then called Bytown), 

 Canada, in 1822. Brought by Bigsby to England, it was figured and 

 described, though not named, by G. B. Sowerby in 1825.'^ E. Forbes, 

 who had the specimen for study, referred to it in his memoir " On the 

 Cystideae of the Silurian Rocks of the British Islands," ^ since the 

 *'■ aspect" of his Agelacrinite^ Buchianus " immediately called [it] to 

 mind"; he even went so far as to say that there could "be no 

 question ... of its being generically allied " to that species. 

 Considering the not unnatural inadequacy of Sowerby's description 

 and figure, the reputation that Forbes had as an authority on 

 echinoderms, and the comparative imperfection of the first found 

 specimens of Edrioaster, it was not surprising that E. Billings in 

 1856 * should have supposed a new Trenton fossil, undoubtedly 

 congeneric with Agelacrinites Buchianus, to be of the same species as 

 that found by Bigsby, and should therefore have applied to it the 

 trivial name ' Bigsbyi,'' while giving to a fossil of obviously difi'erent 

 structure the name ^Agelacrinites Dicksoni.''^ In February, 1858, 

 Billings travelled to London with the fossils in question, and found 

 that Bigsby's specimen was not, after all, the same as his Cyclaster 

 Bigshyi, but was specifically identical with his A. Diehsoni. He 

 redescribed the species, and had his type-specimen, as well as Bigsby's 

 fossil, figured by C. R. Bone.** 



The latter specimen was said by Billings to be then "in the Museum 

 of Practical Geology, Jermyn Street, London." I therefore supposed 

 that it had been transferred to the British Museum when all the 

 foreign fossils were so transferred some years ago. But when no trace 

 of it could be found either in the collections or the registers of that 

 establishment, I applied to Mr, E. T. Newton, palaeontologist to the 



^ Studies I and II were published in the Geological Magazine for December, 

 1898, and May, 1900. Publication of the present Study, written in 1899, Avas 

 delayed owing to an unwillingness to load Zoology with a new generic name without 

 further confirmation from all available evidence. Since that date so much 

 Edrioasteroid material has passed through my hands that the publication of these 

 Studies is resumed with more confidence. 



- "Notice of a Fossil belonging to the Class Eadiaria, found by Dr. Bigsby in 

 Canada" : Zool. Journ., vol. ii, pp. 318-20, pi. xi, fig. 5 ; London, October, 1825. 



3 Mem. Geol. Sm-v. Gt. Brit., vol. ii, pt. ii, 1848 ; see pp. 519 and 520. 



* Eep. Progress Geol. Sm-v. Canada, 1853-6, p. 292; Toronto, Autumn of 1857. 



5 Op. cit., p. 294. 



^ Canadian Organic Remains, dec. iii, p. 84, pi. viii, figs. 3 and 3a (the holo- 

 type) , 4 and 4ff (Bigsby's specimen) . 



