NAUTILI D^. 
311 
placed on the greatest convexity of the volutions. Siphuncle 
subcentral ” (d/orm.) 
BemarTcs. There are only two species Avith which Xautilus Scuvhji 
is strictly comparable, viz., N. LaVierianus, d’Orbigny \ from the 
Upper Xeecomian of France and Switzerland, and N. VaeJsensIs, 
Fig. 68. 
Nauti/ns {Hercoglos!<a) Saxhgi. — a, lateral view of a cast, sliuw’iag the curvature 
of the sutures; b, periplieral view, showing the sulcation of the periphery. 
The last chamber (shaded dai’k) is coated with iron-pyrites. Drawn from 
a specimen (No. 47019 — Morris’s type) in the British Museum. Rather 
more than two thirds natural size. 
Binkhorst^, from the Middle Chalk of Limbourg. N.Saxhyi differs 
from N. Lcdliericmus in its more compressed form, closed umbilicus, 
and more strongly lobed sutures : from N. Vaelsensis it differs 
in its closed umbilicus, more rapidly increasing whorls, sinuous 
sutures, and smooth shell. 
The highly compressed form and the narrow, truncated, and 
channelled periphery characterizing this little group of species dif- 
ferentiate it completely from other forms of the Cretaceous rocks, 
and it is necessary to go back to the Trias in search of species in 
any way resembling it. Here we hud such species as Nautilus 
^ Paleontologie Fran^., Terr. Cret. 1840, vol. i. p. 620. Also Pictet and 
Campiche, Terr. Cret. des Environs de Sainte-Croix, Pal. Suisse, 1859, ser. ii. 
p. 148, pi. xix. ff. 6, a-c. 
^ Mon. des Gasteropodes et des Oephalopodes de la Craie Superieure du 
Limbourg, 1861, p. 15, pi. V<?. ff. 2, a-c. 
