82 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



Vestinautilus CARiNiFERUS, J. ds C. Soioerbj/, sp. Plates XXIII, figs. 1 — 3 ; 



XXYIII, figs. 2 a, h. 



1825. Nautilus cabinifebus, /. de C. Sowerhy. Miu. Conch., vol. v, p. 130, 



pi. cccclxxxii, tig. 3 (excl. fig. 4). 

 ? 1825. — BIANGULATUS, J. de C. Sowerhy. Min. Conch., vol. v, p. 84, 



pi. cccclviii, fig. 2 (two figs.). 

 1828. — EXCAVATUS, Fleming. History of British Animals, p. 231. 



1836. — CABINIFEBUS, J. Phillips. Geology of Yorkshire, pt. 2, p. 232, 



pi. xvii, fig. 19. 

 1836. — SULCIFEEUS, /. Phillips. Ibid., p. 232. 



1844. — (Temnocheilus) cabinifebus, F. M'Coy. Synop. Carb. Toss. 



Ireland, p. 20. 

 1855. — cabinifebus, F. Bl'Coy. British Palaeozoic Fossils, fasc. 3, 



p. 557. 

 1889. CffiLONAUTiLus CABINIFEBUS, A. H. Foord and G. C. CricTc. Gaol. Mag., 



dec. 3, vol. vi, p. 494, figs, a to D. 

 1891. — — A. H. Foord. Cat. Foss. Ceph. British 



Museum, pt. 2, p. 112, fig. 15 a to d. 

 1893. Vestinautilus cabinifebus, A. Hyatt. Carboniferous Cephalopods. 



Second paper. Geological Survey of 

 Texas, Fourth Annual Eeport, 1892, 

 p. 420. 

 \_Not 1844. Nautilus cabinifebus, L. O. de Koninck. Descrip. Anim. Foss. Terr. 



Carb. Belgique, p. 549, pi. xlviii, figs. 11, 12 ; 

 1878, Faune Calc. Carb. Belgique (Ann. Mus. 

 Eoy. d'Hist. Nat. Belgique, torn, ii), pt. 1, 

 p. 134, pi. xxviii, figs. 1 — 5. 



Description. — Shell thick-discoid, subglobose, subhexagonal in transverse 

 section, the whorls all exposed in a large, funnel-shaped umbilicus, which has a 

 small central vacuity. The umbilicus is bordered in the young and adolescent 

 stages of growth by a prominent rim or keel, which becomes gradually obsolete 

 on the body-chamber of the adult shell. The whorls overlap so as to conceal the 

 rim, excepting for the last half-whorl ; in approaching the edge of the aperture, 

 where the whorl narrows a little, the rim is again completely exposed (PI. XXIII, 

 fig. 1 a). The periphery of the adult shell, seen in profile, rises into a low arch 

 which is slightly depressed in the centre ; while on each side one or two faint, 

 obtuse ridges or keels appear, and from these the periphery abruptly descends on 

 each side to the keels bordering the umbilicus. 



In the young shell very strong and prominent ventral ridges are developed, and 

 persist for the first three whorls, when they begin to become weak and fade into 



