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. fitsiformis — 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 Parkins(m's Or- 

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



2. B. ListerL — 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, Avith one or more longitu- 

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



4. B. Jllani 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. 



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

 by partitions destitute of a syphon ; mouth half closed. 



1. C. quadrisulcata — Four-sided, straight, transversely sulcated, 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 strire are most conspicuous witliin the hollows. Two of the op- 

 posite are longer than the others. A curious fossil — Ure''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 pan near the apex is 

 more conical Soiver. Min. Conch, t. cclx. f. 1 2. — In Carboniferous limestone. 



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

 parent. 



* Surjhcc 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. 

 Soicer. 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 hall' 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 Munster ChfF. 



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- 



