Foord and Crick — On Prolecanites compressus. 17 



This species has been referred also to Ceratites,^ Aganides,'^ and 

 Goniatites,^ usually, however, to the latter. 



Owing to the badness of the figure which accompanies his descrip- 

 tion, de Montfort's genus Agdnides^ has been variously interpreted^; 

 but, whatever de Montfort's figure is intended to represent,^ Sowerby's 

 A. Hensloivi is a very different shell, as regards both form and suture- 

 line, and certainly cannot be assigned to the genus Aganides. 



Although placed in the genus (Jeratites by de Haan,' the author of 

 the genus, the suture-line of Ceratites, as that genus is now restricted, 

 differs widely from that of A. Henslowi. 



Ammonites Henslowi is referable to the genus Goniatites, of authors, 

 but this, like Ammonites, is now considerably subdivided. The division 

 into which Sowerby's species falls has been named by Mojsisovics 

 Prolecanites,^ and it is to this genus that Sowerby's species is now 

 usually referred." 



(h) Next as to the species : — 



Of the two names given by Sowerby, JSllipsoUtes compressus was 

 described in 1813, and Ammonites Henslowi in 1820; therefore, 

 according to the law of priority, the specific name compressus must 

 supersede that of Henslowi. 



Hence the name of the shell under consideration becomes Prole- 

 canites compressus ; and Ellipsolites compressus, J. Sowerby, and 

 Ammonites Henslowi, J. Sowerby, are synonyms of it. 

 EXPLANATION OF THE PLATE I. 

 Prolecanites compressus, J. Sby., sp. 

 Fig. 1. Lateral aspect of a speuimeu in the collection of Mr. Joseph Wright, 

 Belfast. About \ nat. size. 

 ,, 2. Front aspect of the same. About \ nat. size. 

 ,, 3. Portion of the test (marked a in Fig. 1). Nat. size. 

 ,, 4. A portion of the periphery, as seen at the point marked h in Fig. 1, showing 



the subangular borders and the sculpture of the shell. Nat. size. 

 ,, 5. The suture-line marked c in Fig. 1. Nat. size. 



„ 6. Suture-line of a specimen (No. C. 3496) from the Carboniferous Limestone, 

 Scarlet, Isle of Man, presented to Brit. Mus. (Nat. Hist.) by Miss C. Birley. 

 Footnote. — While this paper was in the press, Mr. Wright has, through one of 

 the writers, kindly presented the specimen (here described) to the British Museum. 



1 Ceratites Henslowi, de Haan, Monog. Ammon. et Goniat., 1825, p. 157. 



2 Aganides Hensloivi, A. D'Orbigny, Prod, de Paleont., vol. i. p. 115; id. F. 

 M'Coy, Brit. Pal. Foss,, 1855, p. 564. 



3 Goniatites Hemloivi, J. Phillips, Geol. Yorkshire, pt. 2, 1836, p. 236, pi. xs. 

 fig. 39; id. d'Archiac and de Veriieuil, Trans. Geol. Soc. [2], vol. vi. 1842, p. 329; 

 id. J. Morris, Cat. Brit. Foss., 2ud ed. 1854, p. 303; id. C. Barrois, El marmol 

 amigdaloide de los Pirineos (Boletin de la Comision del Mapa geologico de Espana, 

 vol. viii.), 1881, p. 9, pi. C. figs. 3«, 35, 3c; id. B. Etheridge, Fossils of the 

 British Islands, vol. i. Pala3ozoic, 1888, p. 311 ; etc. 



* Conchyliologie systematique, 1808, vol. i. p. 30. 



s See notes on de Montfort's genus by F. B. Meek, Geol. Surv. Territ., vol. ix, 

 1876, p. 494. 



6 P. Fischer (Manuel de Conchyliologie, 1880-87, p. 380) states that the species 

 figured by de Moutfort is Goniatites rotatorius, de Koninck. 



' Monog. Ammon. et Goniat., 1825, p. 157. 



8 E. v. Mojsisovics, Abhandl. d. k.k. geol. Reichsanst., vol. x. 1882, p. 199. 



3 Prolecanites Hensloivi, E. v. Mojsisovics, loc. cit. ; id. K.'A. von Zittel, Handb. 

 d. Palajont., vol. i. 1884, p. 421 ; id. E. Holzapfel, Palseont. Abhandl., Dames and 

 Kayser, n.s. vol. i. 1889, p. 42, pi. iii. fig. 14, pi. iv. figs. 2, 4, 7 ; Goniatites 

 {Prolecanites) Hensloivi, j. Seunes, Comptes Rendus, vol. cxv. 1892, p. 681. 



DECADE IV. — VOL I. — NO. I. 2 



