26 



MOLLUSCA. 



Ammonites. 



149. A. ANGUILIFERUS. — The Hook-Ribbed Ammonite, pi. 



XVIII. fig. 15. 



Ammonites anguiliferus. Phillips, Geologj' of Yorksliire, 

 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. 



130. A. LoscoMBi. — Loscombe's Ammonite, pi. XIX. fig. 1. 



Anmiojiites Loscombi. Sovverbv, 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 tlie 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. GEOMETRicus. — 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. coNSTRiCTUS The Constrained Ammonite, pi. 



XIX. fig. 3. 



Ammonites constrictus. 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 manj' 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 Dundry ; also in the Baculite Limestone of 

 Normandy, and in the Chalk at Lublin, Poland. 



153. A. Henslowi. — Henslovv's Ammonite, pi. XIX. fig. 4. 

 Ammonites Henslowi. 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 on each side, destitute of foliations ; the lobes 

 are pointed inwards, and the intermediate saddles are rounded 

 outwards ; the siph uncle 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. Henslow, Esq. 



This species belongs to the genus Goniatites of Von Buch ; 

 as well as the Ammo}iites striatus, pi. I^^ fig. 6, spharicus, 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. Hawskerensis. — The Hawsker Ammonite, pi. 

 XIX. fig. 6. 



Ammonites Hawskerensis. Phillips, Geology of Yorkshire, 

 L 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. — VValcot's Ammonite, pi. XIX. fig. ?• 

 Ammonites JVcdcotii. 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 Lackington 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 Boulbj', Yorkshire, in the upper Lias Shale. 



158. A. Lythensis. — The Lytli 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 



