240 MOLLUSCA. CEPHALOPODA. Conularia. 



Gen. BELEMNITA. — Apex solid, having a conical cavity 

 towards the base occupied by a shell divided transversely in- 

 to chambers, with a syphon. 



1. B. fusiformis — A receptacle for the alveolus exists towards the base in 

 the form of a cone, from the point of which the body of the fossil again swells, 

 and continues of a compressed roundish shape, with a longitudinal sulcus for 

 an inch or two, when it terminates with a tapering point Parkinson's Or- 

 ganic Remains, iii. 127- t. viii. f. 13 — In Lower Oolite, Stonesfield, Oxford. 



2. B. Listen. — Subfusiform, cylindrical, with one longitudinal sulcus, apex 

 pointed. Siphunculus central, extending through the alveolus to the apex 

 of the spathose part. — B- min. List. An. Ang. 227, f- 32. B. List. Mant. 

 Fossils, 88, t. xix. f. 17, 18. 23.— In Chalk.Marl. 



3. B. coniformis — Conical or produced, pointed, with one or more longitu- 

 dinal grooves Park. Or. Rem. iii. 127- t. viii. f. 15. — In Lias. 



4. B. Allani Nearly cylindrical, the apex conical, with a slender produced 



point. Alveolus conical, pointed, the point sublateral — Belemnite, Allan, 

 Edin. Trans, ix. p. 407- t. xxv. Mant. Fossils, 201, t. xvi. f. 1 In Chalk. 



Many species, not yet determined, occur in the chalk lias, and interme- 

 diate beds. i 



Gen. CONULARIA. — Conical, hollow, divided into chambers 

 by partitions destitute of a syphon ; mouth half closed. 



1. C. quadrisuleata. — Four-sided, straight, transversely sidcated, and longi- 

 tudinally striated ; the four angles sulcated. In the centre of each side, the 

 sulci are bent, the spaces between these form very narrow ridges, and the 

 longitudinal stride are most conspicuous within the hollows. Two of the op- 

 posite are longer than the others. A curious fossil — lire's Ruth. 330. t. xx. f. 7. 

 — Con. quad. Sower. Min. Con. t. ccxl. f. 3, 4, 5, 6. — Carboniferous Limestone. 



2. C. teres — Conical, round, slightly bent, transversely striated, a smooth 

 space near the apex ; striae irregular, as well as the curvature ; the general 

 form approaches towards cylindrical, but the smooth part near the apex is 

 more conical — Soicer. Min. Conch, t. cclx. f. 12 In Carboniferous limestone. 



Gen. AMMONITA. — Sides equal, whorls contiguous and ap- 

 parent. 



* Surface of the whorls smooth. 



1. A. Henslowi Discoid, sides flat, front rounded ; whorls 4, exposed ; par- 

 titions with three entire tongue-shaped lobes on each side ; aperture obovate. 

 Sower. Min. Conch, t. cclxii In Transition Limeston ? Scarlet,Isle of Man. 



** Surface striated or ribbed. 



2. A. acuta Depressed, whorls 3 or 4, the inner ones half exposed ; sur- 

 face with straight projecting radii on the inner half of each whorl; the mar- 

 gin slightly carinated, and crenated ; aperture triangularly cordate — Sower. 

 Min. Conch, t. xvii. f. 1 — In the London Clay at Minister Cliff. 



3. A. cordata Depressed, whorls 4 or 5, the inner ones half exposed ; sur- 

 face with angular, projecting, undulating radii, extending over the inner 

 half of each whorl, the remaining half covered by diverging undulations, end- 



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