230 
NAUTILOIDEA. 
Nautilus excavatus, J. de C. Sowerby. 
1826. Nautilus excavatus, J. de C. Sowerby, Min. Conch, vol. vi. p. 55, 
pi. dxxix. f. 1. 
1842. Nautilus excavatus, d’Orbigny, Paleontologie Fran^aise (Terrains 
Jurassiques), vol. i. p. 154, pi. xxx. 
1849. Nautilus excavatus, d’Orbigny, Prodrome de Paleontologie Strati- 
graphique, vol. i. p. 260. 
1852. Nautilus excavatus, Giebel, Fauna der Vorwelt, Band iii. Abth. i. 
p. 160. 
1854. Nautilus excavatus, Morris, Catalogue of British Fossils, 2nd ed. 
p. 306. 
1858. Nautilus excavatus, Ooster, Catalogue des Cephalopodes Fossiles 
des Alpes Suisses, pt. iii. p. 8. 
1860. Nautilus excavatus, Coquand, Synop. des Foss. Second, de la 
Charente, de la Charente-Tnferieure, et de la Dordogne, p. 9. 
1860. Nautilus excavatus, Wright, Quart. Journ. Geol. Soc. vol. xvi. 
pp. 23, 24. 
1878. Nautilus excavatus, Bayle, Explication de la Carte Geologique 
de la France, vol. iv., xVtlas, pi. xxxvii. 
1879. Nautilus excavatus, Stoddart, Proc. Bristol Naturalists’ Soc. vol. ii. 
pt. iii. p. 279. 
1883. Endolobus excavatus, Hyatt, Proc. Boston Soc. Nat. Hist. vol. 
xxii. p. 288. 
1884. Nautilus excavatus, Mallada, Boletin de la Comision del Mapa 
Geologico de Espana, vol. xi. Sinopsis de las Especies Fosiles de 
Espana, p. 228. 
Ep. Char, “ Nearly globose, smooth ; sides excavated by a very 
large conical umbilicus. . . . The whorls of this Nautilus increase 
very rapidly : they are so wide that they would produce a spherical 
form, were it not for the large umbilicus which occupies nearly half 
the diameter of the shell. The front of the aperture is arched ; 
the sides straight, converging towards the preceding whorl; the 
siphuncle nearly central.” (Sowerby.) 
Bemarl'S. This species is distinguished from all other Jurassic 
forms by the extraordinary width of the aperture in comparison 
with the height, and by the great size and depth of the umbilicus. 
All the inner whorls are exposed in the umbilicus, which has a 
small central perforation. There is a well-developed dorsal lobe. 
Hyatt ^ regards this species as the “ latest survivor” of the Car- 
boniferous genus Endolobus of Meek and Worthen ( — Temnocheilus), 
and there is certainly a considerable resemblance between the 
present species and Nautilus spectahilis, M. & W. the type of 
^ Proc. Boston Soc. Nat. Hist. vol. xxii. 1883, p.^ 288. 
^ Geol. Surv. of Illinois, 1866, vol. ii., PaliEoiitology, p. 308, pi. xxv. if. 1 «, 1 b. 
