‘24 
within the circumference of the small, shallow umbilicus ; 
outer volution very large, its sides rather convex, ornamented 
with slightly elevated, smooth, waved, alternately long and 
short ribs, or undulations ; ambit obtuse, the carina large and 
prominent; aperture sagittate, occupying a half of the dia¬ 
meter of the disk; the size of the umbilicus being a third of 
the remaining half. 
In young shells, the inner volutions are exposed, the 
umbilicus larger, the ribs more conspicuous, and the aperture 
square and oblong, less in proportion to the size of the disk; 
as the shell enlarges, it becomes longer, more deeply indented 
by the preceding volution, and more narrowed towards the 
front. 
Discovered in the Inferior Oolite at Dundry, by G. W. 
Braikenridge, Esq. and occurs in the same strata, Normandy. 
132. A striatulus. — The Minutely-Striated Ammonite, 
pi. XVII. tig. 8. 
Ammonites striatulus. Sowerbv, Min. Conch. V. p. 23, 
pi. 421, tig. 1. Fleming, Brit. An. p. 244. De la Beche, 
Geo. Manuel, p. 371. 
Discoidal, carinated; with six convex, entirely exposed 
volutions ; sides with numerous slender, doubly undulated 
ribs ; the whole surface covered with minute striae, which lie 
parallel to the ribs ; carina but slightly produced ; aperture 
elliptical, its length being about a fourth the diameter of the 
disk. 
Discovered in a Marly Limestone nodule, in Robin Hood’s 
Bay, Yorkshire, by Mr Crawford of Scarborough ; and occurs 
not unfrequently in the Inferior Oolite and Lias of Yorkshire. 
133. A. Banksii.—B anks’s Ammonite, pi. XVII. fig. 9. 
Ammonites Banksii. Sowerby, Min. Conch. II. p. 229, 
pi. 200. Fleming, Brit. An. p. 245. De la Beche, Geo. 
Manuel, p. 373. 
Discoidal ; umbilicate very thick, with five or six rounded 
volutions, with their margins well relieved; sides concave, 
provided with a row of ten or eleven large, round, obtuse 
tubercles ; back slightly convex, and with a series of oblique 
fluted grooves, towards the aperture ; inner volutions narrow, 
the outer one very thick, and equal to the remainder of the 
disk; aperture transverse, its length thrice its width. 
Found in the Inferior Oolite, Dundry. 
Named in honour of the late distinguished friend of science, 
Sir Joseph Banks. 
134. A. rust ic us.—The Rude Ammonite, pi. XVII. fig. 10. 
Ammonites rusticus . Sowerby, Min. Conch. II. p. 171, pi. 
177- Fleming, Brit. An. p. 245. De la Beche, Geo. Manuel, 
p. 293. Man tell, Geology of Sussex, p. 199* 
Depressed; with about three gibbous exposed volutions, 
each provided on both sides with a row of conical obtuse 
tubercles, and two rows of slightly elevated ones around 
the broad and flattened ambit, the bases of the larger ones 
spreading widely, and nearly connected; aperture'wider 
than long, its inner side concave, and considerably shorter 
than the other angles. 
This is a ponderous clumsy species, and is of frequent 
occurrence in the Lower Chalk at Southerham, but the speci¬ 
mens are very imperfect. Sowerby says it occurs at Comb 
Payne, near Lyme Regis, Dorsetshire. It is also met with 
in the Lower Chalk of Lewes, according to Man tell. 
This Ammonite has some affinity to A. catinns , pi. XIII. 
fig. 4, but is distinguished by the two dorsal rows of tubercles, 
and the gibbous form of the volutions. 
Ammonites. 
135. A. marginatus. — The Bordered Ammonite, pi. 
XVIII. fig. 1. 
Ammonites marginatus. Phillips, Geo. Yorkshire, I. p. 
123, pi. 2, fig. 41 and 43. De la Beche, Geo. Manuel, p. 2Q4. 
Subglobose ; umbilicate ; carinate ; the edges of the inner 
volutions only visible in the large deep and conical umbilicus ; 
which has a subcarinated margin, and a series of round, pro¬ 
minent tubercles along its edge ; outer volution very large, 
thick, and slightly wrinkled transversely ; carina prominent 
and sharp. 
The young shell is destitute of tubercles on the margin of 
the umbilicus. 
Found in the Speeton Clay, Yorkshire. 
136. A. maculatus. —The Spotted Ammonite, pi. XVIII. 
fig. 2. 
Ammonites maculatus. Phillips, Geology of Yorkshire, I. 
p. 163, pi. 13, fig. 11. De la Beche, Geo. Manuel, p. 37 L 
Discoidal thick ; with five or six exposed volutions, with 
flattened sides, crossed by numerous, straight, elevated ribs, 
which emanate from the inner margins, and pass over the 
broad, flat ambit, proceeding continuously to the inner 
margins of the volutions on the opposite side ; aperture nearly 
orbicular. 
Found in the Lias of Yorkshire. 
137. A. sigmifer —The S. Ribbed Ammonite, pi. XVIII. 
fig. 3. 
Ammonites sigmifer. Phillips, Geology of Yorkshire, I. p. 
164, pi. 13, fig. 4. De la Beche, Geo. Manuel, p. 37-. 
Discoidal, carinated; with four somewhat compressed 
volutions, crossed by rather distant curved ribs, which 
emanate from the inner edges of the volutions, and after 
passing the centre, bend elegantly forward ; inner volutions 
half concealed and increasing rapidly ; carina sharp and broad 
for the size of the shell. , 
Found in Calcareous nodules, in the Lias formation of 
Yorkshire. 
138. A. discus. —The Quoit Ammonite, pi. XVIII. fig. 4. 
Ammonites discus. Sowerby, Mm. Conch. 1. p. 37, pi. 12. 
De la Beche, Geo. Manuel, p. 373. 
(See description, page 12, No. 48.) 
Found in the Inferior Oolite, Dundry, Yorkshire; and in 
the Cornbrash, middle and south of England. 
139. A. compressus. — The Compressed Ammonite, pi. 
XVIII. fig. 5. 
Ellipsolites compressus. Sower by, Min. Conch. I p. 8 4, 
pi. 38. 
Elliptical, compressed, smooth; with four or five flat 
volutions, almost entirely exposed ; internal margin of the 
volutions flat, perpendicular to the sides ; ambit broad and 
flat; aperture oblong and rectangular. Greatest diameter 
seven inches and a quarter. 
Found in the Limestone at the Black Rock, Ireland. 
140. A. multicostatus. —The Many-Ribbed Ammonite, 
pi. XVIII. fig. 6. 
Ammonites multicostata. Sowerby, Min. Conch. V. p. 76, 
pi. 454. Fleming, Brit. An. p. 247- De la Beche, Geo. Manuel, 
p. 375. 
Discoidal, much depressed ; carinated, with three or four 
entirely exposed volutions; crossed by numerous, strong, 
sharp, slightly bent ribs, which are suddenly curved forward, 
with a depressed, blunted, oblong tubercle on the outer 
extremity of each, and extending over the ambit almost to 
MOLLUSCA. 
