History of British animals - University of Guam Marine Laboratory

240 MOLLUSCA. CEPHALOPODA. Conularia.Gen. BELEMNITA.— Apex solid, having a conical cavitytowards the base occupied by a shell divided transverselyintochambers, with a syphon.1. B. fusiformis —A receptacle for the alveolus exists towards the base inthe 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 foran inch or two, when it terminates with a tapering point Parkinson's OrganicRemains, iii. 127- t. viii. f. 13—In Lower Oolite, Stonesfield, Oxford.2. B. Listen.— Subfusiform, cylindrical, with one longitudinal sulcus, apexpointed. Siphunculus central, extending through the alveolus to the apexof 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 longitudinalgrooves Park. Or. Rem. iii. 127- t. viii. f. 15.— In Lias.4. B. Allani Nearly cylindrical, the apex conical, with a slender producedpoint. 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 intermediatebeds.iGen. CONULARIA.— Conical, hollow, divided into chambersby partitionsdestitute of a syphon;mouth half closed.1. C. quadrisuleata.— Four-sided, straight, transversely sidcated, and longitudinallystriated ;the four angles sulcated. In the centre of each side, thesulci are bent, the spaces between these form very narrow ridges, and thelongitudinal stride are most conspicuous within the hollows. Two of the oppositeare longer than the others. A fossil— curious 6.— lire's Ruth. 330. t. xx. f. 7.—Con. quad. Sower. Min. Con. t. ccxl. f. 3, 4, 5, Carboniferous Limestone.2. C. teres— Conical, round, slightly bent, transversely striated, a smoothspace near the apex striae ; irregular, as well as the curvature ; the generalform approaches towards cylindrical, but the smooth part near the apex ismore conical—Soicer. Min. Conch, t. cclx. f. 12 In Carboniferous limestone.Gen. AMMONITA.— Sides equal, whorls contiguous and apparent.* Surface of the whorls smooth.1. A. Henslowi Discoid, sides flat, front rounded ; whorls 4, exposed ; partitionswith 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 ; surfacewith straight projectingradii on the inner half of each whorl; the marginslightly 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 ; surfacewith angular, projecting, undulating radii, extending over the innerhalf of each whorl, the remaining half covered by diverging undulations, end-4