1. Belemnitella mucronata. [Lign. 141], fig. 1.—The name Belemnitella is given to those Belemnites which have a slit, or crevice, on the anterior margin of the alveolus or cavity, and two lateral impressions. The surface is sometimes granulated, and often has vascular markings, produced by the investing integument of the living animal. The form of the aperture is shown in the middle dextral figure; and the radiated structure, as seen by a transverse section, in the sketch.
This species is abundant in the White Chalk, particularly in certain localities in Norfolk and Devonshire. It is more frequent in the chalk of Kent than in that of Sussex; and in the cretaceous strata around Brighton, than in those near Lewes. I have never been able to detect the least vestige of the phragmocone, or chambered shell, in the alveolus. This Belemnite is occasionally imbedded in flint nodules; and such examples possess the calcareous crystalline structure of the chalk and limestone specimens. In the chalk of Ireland, the Belemnites which have been corroded, or perforated by marine borers (cliona), are often injected with flint; and if the calcareous substance be removed by immersion in dilute hydrochloric acid, exquisite siliceous casts may be obtained (see also page 403). It is not unusual to find flints with a cavity, occasioned by the solution and removal of the calcareous guard, and having a siliceous conical cast of the alveolus, occupying the upper part of the interspace. The reader will recollect that the pulley-stones of the Derbyshire Encrinites were produced by a similar process (see [p. 285], vol. i.).
The American cretaceous sands abound in a species of Belemnitella, nearly related to B. mucronata.
2. Belemnites Listeri. [Lign. 142], fig. 3.—This small elegant Belemnite has two lateral grooves, and is generally as transparent as amber; it has frequently a nacreous or calcareous pellicle partially investing the guard. It seldom exceeds two inches in length. It is abundant in, and peculiar to, the Galt, or blue marl of the Chalk, and is constantly associated with the Inocerami, previously described as common at Folkstone, Bletchingley, Ringmer, and other localities of that deposit. The Red Chalk of Norfolk contains the same species (Min. Conch. tab. 589).
3. Belemnites dilatatus. [Lign. 141], fig. 4.—This species is distinguished by its flattened form, and by the longitudinal furrow being situated on the margin opposite to the siphuncle of the phragmocone, instead of being on the same side, as is most usual. It is supposed by M. D’Orbigny to be characteristic of the Neocomian beds, or lowermost division of the Shanklin Sand.
4. The Chalk-marl contains a Belemnite of a more elongated form than those above described, the apex gradually tapering to a point, with a slight double furrow on each side. It is named B. lanceolatus (Sow. Min. Conch. tab. 600, figs. 8, 9), and is very common in the marl-pits at Steyning, Clayton, and Hamsey, in Sussex.
At the base of Golden Cap Hill, near Charmouth, there are two strata of marl-stone observable on the shore, which are literally paved with Belemnites. Great numbers of these fossils have Serpulæ and other extraneous shells attached to them, a proof that the ink-bags and other soft parts of the mollusks had decomposed, and that the guards had lain uncovered at the bottom of the sea.
M. De Koninck has discovered in the Devonian limestone of Belgium, at Couvin and Visé, a small fossil body which closely resembles in form and structure the rostrum or guard of a belemnite; it is, however, too fragmentary to admit of positive detemination.[404]
[404] Bulletin del’Académie Roy ale de Bruxelles, tome x. No. 3. p. 207.
BELEMNOTEUTHIS