MOLLUSCA. 
Nautilus. 
34 
29, fig. 1. Fleming, Brit. An. p. 231. De la Beche, Geo. 
Manuel, p. 429- 
Almost globose, very largely umbilicate; umbilicus the 
shape of a reversed cone, occupying nearly half the diameter 
of the shell, and producing an excavated appearance in the 
sides; sides smooth, straight, slightly convergent towards 
that part where the volution enters the aperture ; aperture 
subquadrangular, considerably produced at the sides by 
the convex extremity of the umbilicus, arcuated in front; 
siphuncle nearly central, or rather a little towards the ambit. 
Found in the Inferior Oolite, Dorsetshire. 
15. N. sulcatus. —The Furrowed Nautilus, pi. XXIII. 
fig- 7. 
Nautilus sulcatus . Sowerby, Min. Conch. VI. p. 137, pi. 
571, fig. 1, 2. De la Beche, Geo. Manuel, p. 429. 
Discoidal ; with four almost wholly exposed volutions; 
sides ventricose, with two large spiral furrows, and two or 
three shallow, broad, smaller ones on each side, upon the 
most elevated part of the gibbose side; one of the furrows 
being concealed in the inner volutions, and with a sharp 
carinated elevation between the two larger furrows ; ambit 
concave, and bounded by sharp margins; aperture one-half 
longer than it is wide, and with its sides indented; siphuncle 
situate immediately opposite the inner indentation ; septa 
numerous, with straight margins. 
Found in the Mountain Limestone at Castlcton. 
16. N. polygon a ms.— The Many-cornered Nautilus, 
pi. XXIII. fig. 8. 
Nautilus polyyonalis . Sowerby, Min. Conch. VI. p. 5G, 
pi. 530. 
Spheroidal umbilicate ; inner volutions entirely concealed ; 
sides compressed, smooth; umbilicus very small; aperture 
large, arcuated, occupying about half the diameter of the 
disk, its reflected extremities nearly concealing the umbilicus; 
siphuncle situate near the outer edge of the septum, and 
composed of many straight tubes, each protruding a little 
beyond the septum which it penetrates, to join the preceding 
tube ; septa distant, considerably concave, with only a slight 
curvature at their edges; thickness equal to about two-thirds 
its diameter. 
Found in the Inferior Oolite, Dorsetshire. 
The whole series of septa have a disjointed aspect. 
17 . N. eiangulatus. —The Two-angled Nautilus, pi. 
XX111. fig. 9 . 
Nautilus biangulatus . Sowerby, Min. Conch. V. p. 84, 
pi. 458, fig. 2. De la Beche, Geo. Manuel, p. 428. 
Discoidal subglobose, umbilicate; inner volutions half 
exposed ; ambit rounded ; umbilicus very large and deep, in 
the form of a reversed cone, with its margins acutely 
carinated ; aperture transversely elliptical, and obtuse at its 
extremities, its width being equal to about fc two-thirds the 
diameter of the disk. 
In the young condition, the extremities of the aperture arc 
angular. 
Found in the Mountain Limestone near Bristol. 
18. N. hexagonus. —The Six-angled Nautilus, pi. XXIII. 
fig. 10. 
Nautilus hexagonus. Sowerby, Min. 'Conch. VI. p. 55 , 
pi. 529, fig. 2 . 
Somewhat cylindrical, and short; umbilicate ; inner volu¬ 
tions entirely concealed; sides depressed, with a conical 
angle near the centre; ambit broad, straight; umbilicus 
small ; aperture sagittate, and truncated on the outer 
extremity ; siphuncle situate near the inner edge of the 
septum ; septa numerous, and but slightly curved. 
Found in the Calcareous Grit at Sbotover Hill, and also at 
Abingdon. 
19. N. globatus. —The Globular Nautilus, pi. XXIII. 
fig. 11, pi. 25, fig. 5, 9. 
Nautilus globatus. Sowerby, Min. Conch. V. p. 129, pi. 
481. De la Beche, Geo. Manuel, p. 428. Phillips, Geology 
of Yorkshire, II. p. 248, pi. 17, fig- 20, 28. 
Subglobose umbilicate; inner volutions few, rapidly in¬ 
creasing, and almost wholly concealed; sides smooth; 
ambit flattened; umbilicus rather small, deep, and provided 
with a subcarinated margin; aperture large, very wide, 
arcuated, and furnished with a deep and wide sinus on the 
back, which divides it into two equal lobes; thickness and 
diameter nearly equal; septa numerous ; there is a small sinus 
formed in the inner end of the aperture by the intrusion of 
the preceding volution ; greatest diameter, six inches. 
Found in the Black Rock at Cork. 
20. N. W oodyvakdii.—W oodward's Nautilus, pi. XXIII. 
fig. 12. 
Nautilus Woodwardii. Sowerby, Min. Conch. VI. p. 138, 
pi. 571, fig. 3. Ammonites Woodwardii , Martin, Petrifac¬ 
tions of Derbyshire, pi. 35, fig. 4, 5. De la Beche, Geo. 
Manuel, p. 429. 
Discoidal, with four or five wholly exposed, rapidly 
increasing volutions; sides of the volutions angular; the 
Yvhale surface provided with many concentric series of 
granulated lines; ambit rounded, and provided with a 
linear sulcus in its centre; aperture obovate, with angulated 
sides. 
Found at Winster, Derbyshire. 
21. N. centralis. —The Central Siphuncled Nautilus, pi. 
XXIV. fig. L 
Nautilus centralis. Sowerby, Min. Conch. I. p. 11, pi. 1. 
fig. 1. Fleming, Brit. An. p. 229. 
Involute umbilicate; inner volutions wholly concealed; 
aperture transversely elongate, and bluntly lunate; siphuncle 
placed quite central; umbilicus large, but not deep, placed 
behind the projecting sides of the aperture; sides smooth; 
septa entire, gently bending, concave, but not recurved at 
their extremities. 
First discovered in Clay, from a well one hundred and 
seventy-five feet deep, in Richmond Park. 
22. N. costa Lis.—The Ribbed Nautilus, pi. XXIV. fig. 2. 
Nautilus costalis. Phillips, Geology of Yorkshire, II. p. 
233, pi. 22, fig. 30. 
Spheroidal, umbilicate; inner volutions wholly concealed; 
sides covered Yvith transverse flutings, or ribs; ridges rising 
from obscure undulations on the margin of the deep umbili¬ 
cus, and terminating in acute projections on the ambit, which 
arc very conspicuous when viewed in profile, with slight 
contractions at intervals, which are parallel to the ridges, 
and also with pretty strong elevated stria?, which lie in the 
same direction as the ridges; aperture lunate. 
This species attains a very large size, sometimes measuring 
fourteen inches. 
Found at Kildare and Queen’s County, Ireland. 
23. N. Ziczac. The Zigzag Nautilus. PI. XXIV. fig. 3. 
Nautilus Ziczac. Sowerby, Min. Conch. I. p. 12, pi. ]. 
Lowest figures. Fleming, Brit. An. p. 231 ; Buckland, 
