Nautilus. 
MOLLUSCA. 
37 
Discovered in the Chalk Marl at Hamsev, by Dr 
Man tell. 
The young of N. clcgans , pi. 25, fig. 10, bears a conside¬ 
rable likeness to this shell, but the striae are stronger in the 
A. expansus , and the aperture is much more expanded. 
41. N. radiatus. — The Rayed Nautilus, pi. XXV. 
fig. 15. 
Nautilus radiatus. Sowerby, Min. Conch. IV. p. 78, 
pi. 356*. Fleming, Brit. An. p. 230. 
Gibbose, umbilicate ; inner volutions one-third inserted, 
the outer one increasing very rapidly ; sides rounded and 
ornamented with curved, radiating undulations, which meet 
upon the back at an obtuse angle ; back or ambit rounded, 
umbilicus of moderate dimensions, and exposing the inner 
volutions and the edges of the septa; aperture nearly circu¬ 
lar, its length and breadth being about equal, exceeding in 
dimensions half the diameter of the disk, and deeply indented 
by the intrusion of the volutions ; greatest diameter six 
inches and a half. 
Found in the Greensand Formation, near Maltor. 
In its aspect, this shell appears to resemble N. elegans , 
pi. 25, fig. 10, and also the N. undulatus, pi. 23, fig. 2. The 
undulations are more numerous than in the latter, there beinir 
at least five or six to each septum, and it is more regularly 
convex ; besides, the deeply indented ambit of the N. 
undulatus , when viewed in profile, will at once distinguish it. 
42. N. discus —The Quoit Nautilus, pi. IX. fig. 4. 
Nautilus discus. Sowerby, Min. Conch. I. p. 39, pi. 13. 
Fleming, Brit. An. p. 230. 
Discoidal, much compressed ; margins flat, consisting of 
five entirely exposed volutions ; aperture oblong, its greatest 
width not exceeding half an inch; its exterior margin nar¬ 
rower than the inner one, and furnished with a notch, result¬ 
ing from a small groove, which encompasses the margin of 
the ambit; chambers numerous ; septa about an eighth of an 
inch apart; siphuncle situate nearest the inner edge of the 
septa. 
Discovered in the dark coloured Limestone, near Kendal, 
Westmoreland. 
This species was, by mistake, engraved among the 
Ammonites. 
Genus VIII.—NUMMULITES.— Lamarck. 
Shell lenticular, disciform, or thick in the middle, and 
attenuated towards the margins; spire internal, multilo- 
cular, covered over by several tables ; volutions gene¬ 
rally numerous, sometimes to the number of twenty ; 
outer partitions complicated, produced, extending and 
uniting on each side of the centre; cells very numerous, 
small, alternate, and formed by transverse, imperforate 
septa, which are convex near the fronts, leaving a fissure 
between each of them and the preceding volutions ; 
their sides narrow, variously curved, and extending to 
the axis. 
1. N. Comptoni -Compton’s Nummulite, pi. XXVI. 
figs. 1, 2. 
Nautilus Comptoni. Sowerby, Min. Conch. II. p. 45, pi. 121. 
Fleming, Brit. An. p. 229. 
Lenticular, obtusely carinated; surface smooth, with about 
ten distinctly marked septa; aperture acutely triangular, 
formed of two arcuated lips ; diameter not a line. 
Discovered by Earl Compton, at Earl Stoke, near War¬ 
minster, Wiltshire, and named in honour of that scientific 
nobleman. 
2. N. variolaria. —The Variable Nummulite, pi. XXVI. 
figs. 3, 4, 5. 
Nummularia variolaria. Sowerby, Min. Conch. VI. p. 76, 
pi. 538, fig. 3. Lenticulitcs variolaria , Lamarck, Env. de 
Paris, p. 168. An. San. Vert, VII. p. 61Q. 
Shell very convex and smooth, with four or five volu¬ 
tions ; margin obtuse; septa about twenty, forming rays near 
the margin. 
This species is not above a line in diameter, is subject to 
considerable variety in thickness, according to its dimensions; 
the septa are more or less visible on its surface, as it is more 
or less opaque. 
Discovered at Stubbington, by J. Holloway, Esq. in 
Pyrites, in the lower part of the London Clay. 
3. N. ljevigata. — The Smooth Nummulite, pi. XXVI. 
figs. 5, 6, 7. 
Nummulites laevigata. Lamarck, Env. de Paris, p. 172. 
An. San. Vert. VII. p. 629. Parkinson, Org. Item. III. 
p. 152 and 158, pi. 10, figs. 13, 14. Mantell, Geo. Sussex, 
p. 269. Sowerby, Min. Conch. VI. p. 75, pi. 538, fig. 1. 
Nummulita laevigata , Fleming, Brit. An. p. 233. 
Lenticular, smooth, consisting of about twelve greatly 
compressed volutions; sides convex, a little plain, except 
having a few elevated dots, and in the centre being slightly 
undulated; margin narrow, somewhat obtuse, and very finely 
striated; aperture narrow. 
This shell is composed of perpendicular fibres, with an 
external and internal semitransparent coating. 
Discovered at Stubbington Cliff, by J. Holloway, Esq. It 
has since been found in Bricklesom Bay, Sussex. 
Genus IX.—BELLEROPHON.— Montfort. 
Shell thick, univalve, unilocular, involute, umbilicate 
on both sides, nearly symmetrical, bicarinated, and 
almost spherical, the last volution enveloping the 
others ; aperture very large, semilunate, arched, and 
terminated by the extremities of the columella or axis, 
which is transverse, and provided with a sinus or notch 
in the outer edge of the lip, between the keels. 
SECTION r.-SHELLS WITH A MESIAL CARINA. 
1. B. tangentialis— The Tangent-Ridged Bellerophon, 
pi. XXVI. figs. 12 and 22. 
Bellerophon tangentialis. Phillips, Geo. of Yorkshire, II. 
p. 230, pi. 17, figs. 6, 7, and 14. 
Cylindrico-globose ; umbilicus largely rounded ; aperture 
much expanded; ambit broad, and provided with an acute, 
narrow carina, from which emanate straight ridges and fur¬ 
rows, which rise perpendicular to the keel, forming tangents 
to the inner margin. 
Found at Bolland, Queen’s County, Ireland. 
K. 
