18 
MOLLUSCA. 
Ammonites. 
90. A. catfnus. —The Chain Ammonite, pi. XIII. fig. 4. 
Ammonites Catinci , Sowcrby, Min. Conch. V. p. 21. pi. 
420. Mantell, Geology of Sussex, p. 198, pi. 22, fig. 10. 
Buckland, Geology and Mineralogy Considered, II. p. 59, 
pi. 37, fig. 8. 
Depressed, with from six to eight smooth volutions, with 
flattened sides, the inner ones exposed; provided with two 
series of short, blunt, moderately sized, conical, round pointed 
tubercles on each side of the interior and exterior angles of 
the volutions ; ambit a little, convex ; aperture quadrangular; 
margins of the septa sharp and deeply sinuated. Largest 
diameter about thirteen inches. 
Little is known of the perfect condition of this fossil, as 
little else has hitherto been found of it but casts of the 
chambers; these have usually suffered so much by the 
destroying hand of time, that they are but slightly attached, 
and appear like the concatenations of a chain. From the 
small portions of the shell which have been seen, it appears to 
be quite smooth, divested of ribs or undulations, excepting 
in its young condition. 
Found embedded in sand, in Marsham Field, near Abing¬ 
don, Berkshire. 
91. A. Parkensoni. — Parkinson’s Ammonite, pi. XIII. 
fig. 5. 
Ammonites Parkinsoni , Sowerby, Min. Conch. IV. p. 1, 
pi. 307- De la Beche, Geo. Manuel, p. 375. Fleming, Brit. 
An. p. 244. 
Discoidal, with from seven to nine slightly convex 
volutions, the inner ones exposed ; crossed by numerous, 
considerably elevated and arcuated ribs, which are bent for¬ 
ward at their exterior ends; they are furcated near the ambit, 
which is narrow and plain, upon which they nearly meet; 
aperture oblong, narrowed towards the back. Greatest 
diameter eighteen inches. 
Found in the Lias at Yeovil, and Ilolienstein, Saxony, and 
in the inferior Oolite, Bayeux. 
92. A. Solaris. —The Sun Ammonite, pi. XIII. fig. 6. 
Ammorntes Solaris , Phillips, Geology of Yorkshire, I. p. 
135, pi. 4. fig. 29 . De la Beche, Geo. Manuel, p. 370. 
Discoidal, earinated, with four nearly flat volutions, the 
inner ones exposed ; provided with numerous elevated smooth 
ribs, reaching entirely across the volutions, and slightly bent 
forward at their exterior ends, where they are terminated 
by the acutely triangular keel; aperture spatuliform, acute 
next the ambit. 
Found in the Calcareous Grit at Scarborough, by Mr Wil¬ 
liamson. 
93. A. MUTABii.is. — The Mutable Ammonite, pi. XIII. 
figs. 7 and 9» 
Ammonites mu ta hi l is, Sowerby, Min. Conch. IV. p. 145, 
figs. 1 and 2. Fleming, Brit. An. p. 246. 
Shell compressed, with from four to five smooth volutions, 
the inner ones two-thirds exposed, exhibiting tuberculated, 
wide set ribs ; ambit rounded; aperture ovato-sagittate. 
Largest diameter ten inches; thickness of external volutions 
an inch and a half. 
Fig. 9 represents the shell in its young state, when there 
is a narrow flattened zone in the centre of the ambit, from 
whence emanate numerous close-set, somewhat curved ribs, 
which extend to about the centre of the volutions, where they 
meet a series of compressed, oblong-ovate tubercles, which 
reach to the inner margin of the volutions; the whole interior 
sides of the volutions are smooth. It is only in the very 
immature state that the tubercles are formed, as they are no 
longer met with in specimens of two inches diameter; but 
the external ribs are visible in specimens of six inches 
diameter, after which they imperceptibly disappear; and 
the ambit becomes more rounded, the sides quite smooth, 
and are somewhat obliquely compressed towards the back, 
which produces the obtuse sagittate form of the aperture. 
The external surface is nacred; and at remote, but unequal 
intervals, there are slight contractions in the volutions. 
Discovered in the Clunch Clay near Horncastle, by George 
Weir, Esq. 
94. A. oculatus.—T he Eyed Ammonite, pi. XIII. fig. 8. 
Ammonites oculatus , Phillips, Geology of Yorkshire, I. 
p. 138, pi. 5, fig. 16. 
Shell compressed, and slightly depressed; umbilicate ; 
interior volutions hidden ; numerous depressed undulating 
ribs emanate from the margin of the umbilicus, and extend 
to near the ambit, where they meet a series of very remote, 
nearly circular, depressed tubercles, between which and the 
back is smooth; a series of close-set oblong tubercles invest 
both sides of the ambit, which is smooth. 
Found in the Oxford Clay at Scarborough. 
95. A. athleta. — The Champion Ammonite, pi. XIII. 
fig. 8. 
Ammonites atlileta . Phillips, Geology of Yorkshire, I. p. 
141, pi. 6, fig. 19. 
Shell strong, with six volutions, the inner ones almost 
wholly exposed; sides crossed by numerous, strong, elevated 
ribs, with an oblong produced tubercle at each end, those on 
the outer margin considerably larger than the others ; eacli 
of these divide into three narrow exserted smooth ribs, on 
the flattened and square ambit, uniting with the tubercles on 
the opposite side ; the interior volutions gradually diminish 
in thickness as they approach the centre, the whole side 
forming a widely reversed cone; aperture nearly quad¬ 
rangular. 
Found in the Kelloways Rock at Hackness, and in the 
Oxford Clay, Yorkshire. 
96. A. tubeuculatus.—T he Tuberculated Ammonite, pi. 
XIV. fig. 1. 
Ammonites tuberculatus . Sowerby, Min. Conch. IV. p. 4, 
pi. 310, fig. 1, 2, 3; Mantell, Geology of Sussex, p. 92; 
Fleming, Brit. An. p. 246; De la Beche, Geo. Manuel, 
p. 294. 
Compressed umbilicate, with five convex volutions, the 
inner ones two-thirds exposed ; ambit flat; transversely ribbed, 
the costae oblong, arising in threes from large circular tubercles, 
uniting in pairs towards the back, and forming large com¬ 
pressed tubercles on each side of the ambit, which is broad, 
with a deep narrow sulcus or groove in its centre ; aperture 
suborbicular ; septa very foliaceous. 
I 11 immature shells, the sides of the volutions are very 
convex, with a transverse aperture ; the tubercles are situate 
near the centre of the volutions. Length of the aperture 
about two-fifths of the diameter of the outer volution, and its 
width varying according to age. 
Found in a stratum of Marie, under the Chalk at Folkstone, 
and in the Blue Chalk Marl at Ringmer, Sussex; also in the 
the same kind of strata at Cambridge, and other parts of 
England. 
This is a strongly marked species, and has somewhat the 
