26 
MOLLUSCA. 
Ammonites. 
149. A. a ngu 1 lifer us.—The Hook-Ribbed Ammonite, pi. 
XVIII. fig. 15. 
Ammonites anguiliferus. Phillips, Geology of Yorkshire, 
I. p. 163, pi. 13, fig. 19. De la Beche, Geo. Manuel, p. 372. 
Discoidal, with five almost wholly exposed volutions, 
crossed by numerous elevated ribs, which pass over the 
rather thin ambit, in a somewhat hooked form; aperture a 
little cordiform. 
Found in the Marlestone and Ironstone series of Yorkshire. 
150. A. Loscombi. —Loscombe's Ammonite, pi. XIX. fig. 1. 
Ammonites Loscombi, Sowerby, Min. Conch. II. p. 185, 
pi. 183. De la Beche, Geo. Manuel, p. 374. 
Discoidal, compressed, umbilicate ; inner volutions con¬ 
cealed ; surface smooth, sides crossed by numerous waved 
flat ribs, with shallow interstices ; back rounded; aperture 
oblong, about two-fifths the diameter of the disk in length ; 
the thickness of the shell a third of the length of the aperture. 
Discovered in the Blue Lias at Lyme Regis, Dorsetshire, 
by C. W. Loscombe, Esq.; found also in the Lias in the 
middle and south of England. 
151. A. geometri'cus. — The Geometrical Ammonite, pi. 
XIX. fig. 2. 
Ammonites geometricus, Phillips, Geology of Yorkshire, I. 
p. 164, pi. 14, fig. 9 . De la Beche, Geo. Manuel, p. 372. 
Discoidal, carinated, compressed ; with five flat, almost 
wholly exposed volutions; crossed by numerous, sharp, 
straight ribs, which gradually thicken as they approach the 
ambit, where they suddenly curve forward, over the edge of 
the flattened back, producing a crenulated appearance when 
viewed in profile; ambit, with a very small, narrow, undu¬ 
lating carina in its centre; aperture narrow, oblong oval. 
152. A. cossTRiCTUS—The Constrained Ammonite, pi. 
XIX. fig. 3. 
Ammonites const rictus, Sowerby, Min. Conch. II. p. 189, 
pi. A. fig. 1. Fleming, Brit. An. p. 247. De la Beche, Geo. 
Manuel, p. 295. 
Discoidal, compressed, umbilicate; inner volutions con¬ 
cealed, sides crossed by many undulating long and short 
ribs ; with a row of acute tubercles on each side of the 
margin of the somewhat rounded ambit; these tubercles are 
usually larger near the centre of the volutions, and gradually 
diminish towards the inner volutions and aperture, which is 
oblong and contracted, by an obtusely edged lip ; septa nume¬ 
rous, and greatly sinuated. 
There is a variety of this species with few tubercles near 
the centre, and those next the front large. 
Found at 1)undry ; also in the Baculite Limestone of 
Normandy, and in the Chalk at Lublin, Poland. 
153. A. IIenslowi. —Henslow’s Ammonite, pi. XIX. fig. 4. 
Ammonites llcnslowi, Sowerby, Min. Conch. III. p. Ill, 
fig. 1, 2, pi. 262. De la Beche, Geo. Manuel, p. 466. Buck- 
land, Geology and Mineralogy Considered, I. p. 360, note, 
and II. p. 60, pi. 40, fig. 1. 
Discoidal; having about four exposed volutions, with 
flattened sides ; ambit rounded, with three simple slipper¬ 
shaped lobes 011 each side, destitute of foliations ; the lobes 
are pointed inwards, and the intermediate saddles are rounded 
outwards ; the siplmncie is placed on the front edge, in an 
acute lobe; aperture about four-fifths the diameter of the 
shell, and double that in thickness. 
Discovered in the Transition Limestone at Scarlet, Isle of 
Man, by J. S. Ilenslow, Esq. 
This species belongs to the genus Goniatites of Von Bucli ; 
as well as the Ammonites striatus, pi. IV. fig. 6, sp/uericus, fig. 
7> and minutus , fig. 10. 
154. A. artigyrus —The Perfectly Round-Ribbed Am¬ 
monite, pi. XIX. fig. 5. 
Ammonites artigerus, Phillips, Geology of Yorkshire, I. 
p. 163, pi. 13, fig. 9* De la Beche, Geo. Manuel, p. 372. 
Discoidal ; with five wholly exposed, slightly rounded 
volutions, their sides crossed by numerous, remote ribs, which 
emanate from the inner margins of the volutions, and crossing 
the sides, proceed continuously over the rounded ambit to 
the opposite side ; aperture suborbicular. 
Found in the upper Lias Shale of Yorkshire. 
155. A. Hawskkrensis. — The Hawsker Ammonite, pi. 
XIX. fig. 6. 
Ammonites Hawsherensis. Phillips, Geology of Yorkshire, 
I. p. 164, pi. 13, fig. 8. De la Beche, Geo. Manuel, p. 372. 
Discoidal, umbilicate, carinate, thick ; with six somewhat 
flattened, wholly exposed volutions, the inner ones becoming 
gradually thinner as they descend to the centre, forming a 
deep umbilicus; the whole are crossed by strong, thick ribs, 
which project boldly over the margin of the flattened ambit, 
and terminate on each side of the carina, which is narrow, 
rounded, and but slightly elevated above the surface ; aper¬ 
ture nearly quadrangular, with its corners slightly rounded, 
and equal to about a fourth the diameter of the disk. 
Found in the hard Shale and Calcareous nodules, at Haw- 
sker, Yorkshire. 
156. A. Walcotii. —Walcot’s Ammonite, pi. XIX. fig. 7« 
Ammonites Walcotii, Sowerby, Min. Conch. II. p. 7, pi. 
106. Phillips, Geology of Yorkshire, I. p. 164. Fleming, 
Brit. An. p. 242. De la Beche, Geo. Manuel, p. 372, and 
384. 
Discoidal, compressed, carinate; with four one-fourth 
inserted volutions ; on the inner side of each is a smooth 
concentric furrow ; external half of the sides crossed by 
numerous semilunar ribs, which are about equal in breadth 
to the intermediate furrows ; on each side of the carina is a 
moderately deep groove; aperture oblong, its length equal to 
one-third of the diameter of the disk : varying in size from 
two to four inches. 
Found in the Lias of Yorkshire, and in the middle and 
south of England ; in the Alum Clay, Whitby ; the Clay 
Ironstone at Colbrook Dale; the Marly Limestone near 
Bath ; and at White Laekington Park. 
157* A. exaratus. — The Ploughed Ammonite, pi. XIX. 
fig- 8. 
Ammonites exaratus, Phillips, Geology of Yorkshire, I. 
p. 164, pi. 13, fig. 7- De la Beche, Geo. Manuel, p. 373. 
Discoidal, lenticular, umbilicate, carinate ; with four volu¬ 
tions, the inner ones almost entirely enveloped in the outer 
one, and visible only in the small umbilicus ; sides somewhat 
flattened, and crossed by broad, flat, undulating ribs, which 
suddenly curve forward towards the ambit, and terminate on 
the edge of the small and narrow carina. 
Found at Boulby, Yorkshire, in the upper Lias Shale. 
158. A. Lytiiensis. —ThcLyth Ammonite, pi. XIX. fig. 9- 
Ammonites Lythensis, Phillips, Geology of Yorkshire, I. 
p. 164, pi. 13, fig. 6. De la Beche, Geo. Manuel, p. 373. 
Discoidal, lenticular, umbilicate ; with four volutions, the 
inner ones being entirely enveloped in the outer volution, 
and their edges only seen in the shallow umbilicus ; sides 
