Foord and Crick — Qyi Prokcariites compressus. 11 



II. — On the Identity of Ellipsolites compressus, J. Sowerby, 

 WITH Ammonites Renslowi, J. Sowerby. 



By Arthur H. Foord, F.G.S., of the Eoyal Dublin Society, Dublin; and 



G. C. Crick, Assoc. E.S.M., F.G.S., 

 Assistant in the Geological Department, British Museum (Nat. Hist.). 



(PLATE I.) 

 (i.) Introduction. 



mLIPSOLITES COMPBESSUS, J. Sowerby (Min. Con. vol. i. 

 p. 84, pi. xxxviii. 1813), has been hitherto usually regarded as 

 a Nautiloid,* and referred either to Nautilus or to Discites. 



During an examination of the collection of Mr. Joseph Wright, 

 of Belfast, by one of the present writers, a fossil from the same 

 horizon, and almost the same locality as the type-specimens of 

 Elli-psolites compressus of J. Sowerby, was observed, so much re- 

 sembling Sowerby's species (but exhibiting also the character of 

 the suture-line) that a comparison with, and a re-examination of, 

 Sowerby's types was suggested. 



Mr. Wright has very kindly lent us this fossil, so that we have 

 been enabled to compare it closely with Sowerby's figured specimens, 

 both of which are in the British Museum (Natural History), and we 

 would take this opportunity of returning to Mr. Wright our sincere 

 thanks for the loan of his specimen, which has served to throw 

 much light upon the character of Sowerby's species. 



When describing his species, Sowerby was evidently unacquainted 

 with the suture-line, for, in speaking of the larger of the two speci- 

 mens which he figured, he says "the crystallization seems to have 

 helped to obliterate the chambers, if there were any," and, in 

 referring to the smaller of the two specimens, he says nothing 

 whatever about the septa. After very careful examination we have 

 not been able to detect any trace of septa in the larger specimen, 

 but in the smaller example the suture-line is somewhat indistinctly 

 visible at about the commencement of the last whorl. 



(ii.) Description and determination of a specimen in the collection of 

 Mr. Joseph Wright, Belfast. 



Mr. Wright's specimen is considerably larger than the larger of 

 the two specimens figured by Sowerby, which, by the way, is a little 



' Nautilus compressus, J. Fleming, Brit. Anim., 1828, p. 231 ; id. De la Beche, 

 Geological Manual, 1831, p. 448; id. Goldfuss, in v. Dechen's Handb. d. Geognosie, 

 1832, p. 536; id. T. Weaver, Trans. Geol. Soc. [2], vol. v. 1837, p. 22; id. L. 

 Agassiz, in E. Desor's Translation of Sowerby's Min. Con. 1842, p. 27 ; id. E. 

 Griffith, Notice respecting the Fossils of the Mountain Limestone of Ireland, as 

 compared with those of Great Britain, and also with the Devonian System, 1842, 

 p. 21 ; id. A. D'Orbigny, Prod, de Paleont., vol. i. 1850, p. 110 ; id. C. G. Giebel, 

 Fauna der Worwelt, vol. iii. 1852, p. 178 ; Nautilus [Discites) compressus, J. 

 Morris, Cat. Brit. Foss., 2nd ed. 1854, p. 308; Nautilus compressus, L.-G. de 

 Koninck, Faune du Calcaire Carbonifere de la Belgique (Annales du Mus. Eoy. 

 d'Hist. nat. de Belgique, vol. ii.), pt. i. 1878, p. 122; Discites compressus, E. 

 Etheridge, Fossils of the British Islands, vol. i. Palaeozoic, 1888, p. 310 ; id. A. H. 

 Foord, Cat. Foss. Ceph. Brit. Mus. (Nat. Hist.), vol. ii. 1891, pp. 86 and 91; id. 

 A. H. Foord and G. C. Crick, Geol. Mag. Dec. III. Vol. X. 1893, p. 253. 



