12 



MOLLUSCA. 



Ammonites- 



of the volutions, and extend to nearly tlie ceiitre, where they 

 are met by numerous obtuse, arcuated ribs, passing over the 

 round ambit ; aperture semilunar, inclining to a transverse 

 ellipsis ; thiel^ness half the diameter of the shell ; septa very 

 numerous, and beautifully sinuated. Greatest diameter 

 upwards of five inches. 



Found in the inferior Oolite, and also at Dundry. 



Named to commemorate that zealous naturalist, the late 

 M. Brocchi of Nice, author of the beautiful work, entitled, 

 " Conchiologis Fossilis Subappennina." 



44. A. SERRATUS The Serrated Ammonite, pi. VIII. 



fig. 10. 



A/nmoJiifes serratus. — Sowerby, Min. Conch. I. p. 65, 

 pi. 24. 



Discoidal, involute, compressed, carinated, having five volu- 

 tions two-thirds inserted; with distant, strong arcuated ribs 

 extending from the ambit to nearly the middle of the volu- 

 tions ; numerous curved costse emanate from the inner margin 

 of the volutions, and nearly meet the others in the centre ; 

 sides of the volutions somewhat concave contiguous to the 

 keel, which is nearly cylindrical, ornamented with sharp 

 crenulations, and containing the siphuncle ; aperture narrow, 

 pentangular, and extending to half the diameter of the shell ; 

 septa close, with numerous deep undulations. Largest 

 diameter four inches, thickness one inch. 



Found in the Marie, parish of Worlingham, near Beccles, 

 Suffolk. 



The central volutions of this species are very thin, and 

 specimens are frequently found without them. 



45. A. SowERBil Sowerby's Ammonite, pi. IX. fig. 1. 



Ammonites Sowerbii. — Miller, MS. Catalogue ; Sowerby, 



Min. Conch. III. p. 23, pi. 213, figs. 1, 2, 3. 



Discoidal, carinated ; with four volutions, the inner ones 

 about half inserted, or, to the base of the tubercles, having a 

 series of about nine or ten spiriform tubercles in the centre of 

 each, placed upon obtuse ridges ; the inner half of the volu- 

 tion smooth, the outer half with numerous, slightly bending 

 ribs, terminating at the keel, which is defined and entire, 

 projecting greatly, rounded externally, and almost separated 

 from the volutions, with the siphuncle placed in its outer 

 extremity ; aperture elliptical. 



Found in the inferior Oolite at Deudry. 



There is a variety of this species with a circular aperture, 

 and the keel sometimes impressed. In this variety the ridges 

 on which the tubercles are seated are more prominent, and 

 the carina so far sunk as to have a furrow on each side. The 

 inner volutions in this variety are less inflated than in the 

 ibrmer. 



46. A. KoENiGi. — Koenig's Ammonite, pi. IX. fig. 2. 

 Ammonites Koenigi. — Sowerby, Min. Conch. III. p. 113, 



pi. 263, figs. 1, 2, 3. 



Discoidal, convex, with six volutions, the inner ones about 

 half inserted ; sides with distant, strong ribs, which assume 

 the form of oblong tubercles, commencing at the inner mar- 

 gins of the volutions, and extending to about the centre, 

 where they are met by numerous, slightly arcuated, gently 

 raised ribs, which extend over the rounded ambit ; aperture 

 cordiform, elongated ; septa few, with slightly sinuated lobes. 



Found at Kelloways and Charmouth. 



In the immature condition this species is more gibbose than 

 in the adult, consequently the aperture is nearly orbicular. In 

 the perfect shell, the last or body volutions occupies about 

 half the diameter of the disk. 



This fossil is named in honour of Dr Koenig, of the British 

 Museum, an excellent geologist. 



47. A. LisTERi. — Lister's Ammonite, pi. IX. figs. 3 and 6. 

 Ammonites Listeri. Martin's Petrifactions of Derbyshire, 



pi. 35, fig. 3. Sowerby, Min. Conch. V. p. 163, pi. 501, fig. 1. 



Subdiscoidal, thickness nearly equal to its diameter, with 

 five or six narrow volutions, the inner ones partly inserted, 

 and deeply sunk ; back or ambit very convex, broad ; sides 

 inversely conical, with numerous, strong sharp ribs, which 

 extend over the ambit, and meet on the opposite side, ter- 

 minating in a series of strong, elevated, pointed tubercles on 

 the inner margin of the volutions ; general size about an inch 

 and a half in diameter, and sometimes reaching two inches. 



Found in the Limestone of Eyem and Middleton, Derby- 

 shire, in a Shale stratum belonging to the coal formation. It 

 occurs in nodules of iron-pyrites or limestone ; also in shale 

 on the Bradford road, about two and a half miles from Hali- 

 fax, Yorkshire. This stratum extends to Idle near Calverly, 

 and to Farsley in the neighbourhood of Horseforth, and 

 stretching in various undulations so far as Leeds. 



This is one of those remarkably thickened species which 

 belong to the same tribe as Ammonites Blagdeni, \)\. 12. fig. 9. 



Remote annular depressions are observable ujjou the inside 

 of the casts of this shell, from which it would appear that the 

 margin of tht aperture was thickened at particular stages of 

 its growth. 



48. A. DISCUS The Quoit Ammonite, pi. IX. fig. 4. 



Ammotiites discus — Sowerby, Min. Conch. I. p. 37, pi- 12, 



figs. 1 and 2. 



Discoidal, umbilicate, much compressed, volutions smooth, 

 much concealed ; outer margin acuminated ; aperture sagit- 

 tate, occupying half the diameter of tiie disk, and one-sixth 

 in breadth ; septa irregularly undulated ; aperture sagittate. 

 Greatest diameter four inches; thickness half an inch. 



Discovered in a stone cjuarrj' near the House of Industry 

 at Bedford. 



49. A. Strakgewaysi Strangeway's Ammonite, pi. IX. 



figs. 5 and 10. 



Ammonites Strangewasii. — Sowerby, Min. Conch. III. 

 p. 'J9, pi. 254, figs. 1 and 3. 



Discoidal, carinated ; five volutions, with their sides nearly 

 flat ; with an oljscure concentric furrow, the margin of the 

 outer one flattened, slanting from the centre, and the inner 

 edges of the others obliquely depressed; the ^hole crossed 

 by numerous slightly raised, twice curved, undulating ribs, 

 which are frequently obscure on the inner side and centre of 

 the volutions, but larger and more determined on the dorsal 

 edge ; each of these ribs forms two semicircles, reversed to 

 one another ; aperture oblong ; occupying nearly one-third 

 of the diameter of the disk. Greatest diameter about six 

 inches. Discovered at llminster. 



50. A. Greenovii. — Greenough's Ammonite, pi. IX. figs. 

 7, and 8. 



Ammonites Greenovii. — Sowerby, Min. Conch. II. p. "1, 

 pi. 132, figs. 1, 2. 



Discoidal, compressed ; volutions four or five, two-thirds 

 inserted, the outer one being nearly half the diameter of the 

 shell ; with obscure ribs, which are most apparent towards 

 the rounded back, over which they pass ; those on the inner 

 volutions quite distinct ; aperture elliptical, with a deep 

 indentation from the insertion of the volution ; siphuncle 

 placed near the centre of the back margin of the aperture ; 

 septa close, greatly and beautifully sinuated, and locked into 



