122 
NAUTILOIDEA. 
S]i. Char. ‘‘ Discoidal, smooth, with many shaq) sigmoidal [trans- 
verse] and some spiral strim ; whorls quadrangular, the back concave 
along the middle, bevelled to the side ; the sides concave toward 
the outer edge and convex toward the abrupt marginal slope; 
sii)huncle near the outer edge, aperture oblong (analogous to N. sul- 
catus).” {Phillips.) 
Remarlcs. Unfortunately Phillips’s type specimen is a cast, so that 
its characters were not fully recognized until the species was figured 
by de Kcninck from more complete specimens. These show that 
there were two sharp keels upon the periphery, separated by a 
shallow channel, which is scarcely perceptible on the type specimen. 
There are not more than three whorls in the present species, not 
five, as described by M‘Coy ; they are all exposed and leave a small 
central perforation. The septa are moderately distant, the sutures 
forming a shallow sinus upon the sides of the shell and bending 
sharply backwards upon the periphery. Fragments of the test ^ 
show that it was covered with very fine lines of growth, curved 
sigmoidally on the sides of the shell, as figured by de Koninck ^ 
It is very doubtful whether the fragment figured b}' Eichwald 
(Leth. lloss. vol. i. pt. ii. p. 1312, pi. xlix. f. 21) under the name 
Nautilus suhsulcatus belongs to the present species. It was found 
in the Lower Carboniferous Limestone near Borowitschi, in the 
Government of Novgorod. 
A species described by dc VerneuiP under the name Nautilus 
hicarinatus may be the young of the present species, judging by the 
description and figure, though de Koninck differentiates it on the 
ground that it is much more rounded in section. 
Horizon. Calcaire de Vise (Assise vi.), = Carboniferous Limestone. 
Localities. British. Bolland, Yorkshire ; Derbyshire ; Isle of 
Man. — Foreign. Vise, Belgium. 
Well represented in the Collection, which contains Phillips's type 
specimen (registered No. C. 237, “ Gilbertson Collection ”). 
Coelonautilus quadratus, Fleming, sp. 
1828. Nautilus quadratus, Fleming, Hist, of British Animals, p. 231. 
1840. Nautilus suhsulcatus, var., J. de C. Sowerby, in Prestwick’s 
‘‘ Geology of Coalbrookdale,” Trans. Geol. Soc. vol. v. pt. hi. 
p. 492, and Explanation of Plates, xl. f. 7. 
1843. Nautilus suhsulcatus, var., Portlock, Geol. of Londonderry, p. 405. 
^ See specimen registered No. C. 238. 
^ Descrip, des Anim. Foss, chi Terr. Carbon, de Belgique, 1844, pi. xlix. f. 4. 
^ Geol. de la Bussie d’Europe, by Murchison, de Verneuil, and de Keyserling, 
vol. ii. pt. iii. p. 364, pi. xxv. ff. 10, a, h. 
