Part 23 (1/2)

Feet.

1. Sand, white, yellowish, or brown, with concretions of limestone and chert 70 2. Sand, with green matter 70 to 100 3. Calcareous stone, called Kentish rag 60 to 80

These divisions, which are traceable more or less from the southern part of the Isle of Wight to Hythe in Kent, present considerable variations.

At Atherfield, where sixty-three distinct strata, measuring 843 feet, have been noticed, the limestone is wholly wanting, and some fossils range through the whole series, while others are confined to particular divisions; but Prof. E. Forbes states, that when the same conditions are repeated in overlying strata the same species reappear; but that changes of depth, or of the mineral nature of the sea-bottom, the presence or absence of lime or of peroxide of iron, the occurrence of a muddy, sandy, or gravelly bottom, are marked by the absence of certain species, and the predominance of others.[79]

[79] Ibid, p. 340.

Among the marine fauna of the Neocomian series the following are the princ.i.p.al. Among the _Acephala_, one of the largest and most abundant sh.e.l.ls of the lower Neocomian, as displayed in the Atherfield section, is the large _Perna Mulleti_ (Fig. 131).

[Ill.u.s.tration: Fig. 131.--Perna Mulleti. One-quarter natural size.

_a_, exterior; _b_, part of the upper hinge.]

[Ill.u.s.tration: Fig. 132.--Hamites. One-third natural size.]

The _Scaphites_ have a singular boat-shaped form, wound with contiguous whorls in one part, which is detached at the last chamber, and projects in a more or less elongated condition.

_Hamites_, _Crioceras_, and _Ancyloceras_ have club-like terminations at both extremities; they may almost be considered as non-involuted Ammonites with the spiral evolutions disconnected or partially unrolled, as in the engraving (Figs. 125 and 132). _Ancyloceras Matheronia.n.u.s_ seems to have had spines projecting from the ridge of each of the convolutions.

[Ill.u.s.tration: Fig. 133.--Sh.e.l.l of Turritella terebra.

(Living form.)]

[Ill.u.s.tration: Fig. 134.--Turrillites costatus.

(Chalk.)]

The _Toxoceras_ had the sh.e.l.l also curved, and not spiral.

The _Baculites_ had the sh.e.l.l differing from all Cephalopods, inasmuch as it was elongated, conical, perfectly straight, sometimes very slender, and tapering to a point.

The _Turrilites_ have the sh.e.l.l regular, spiral, and _sinistral_; that is, turning to the left in an oblique spiral of contiguous whorls. The engraving will convey the idea of their form (Fig. 134).

Among others, as examples of form, we append Figs. 133, 135, 136.

This a.n.a.lysis of the marine fauna belonging to the Neocomian formation might be carried much further, did s.p.a.ce permit, or did it promise to be useful; but, without ill.u.s.tration, any further merely verbal description would be almost valueless.

[Ill.u.s.tration: Fig. 135--Terebrirostra lyra.

_a_, back view; _b_, side view.]

[Ill.u.s.tration: Fig. 136.--Terebratula deformis.]

Numerous Reptiles, a few Birds, among which are some ”Waders,” belong to the genera of _Palaeornis_ or _Cimoliornis_; new Molluscs in considerable quant.i.ties, and some extremely varied Zoophytes, const.i.tute the rich fauna of the Lower Chalk. A glance at the more important of these animals, which we only know in a few mutilated fragments, is all our s.p.a.ce allows; they are true medals of the history of our globe, medals, it is true, half effaced by time, but which consecrate the memory of departed ages.

In the year 1832 Dr. Mantell added to the wonderful discoveries he had made in the Weald of Suss.e.x, that of the great Lizard-of-the-woods, the _hylaeosaurus_ (???, _wood_, sa????, _lizard_). This discovery was made in Tilgate forest, near Cuckfield, and the animal appears to have been from twenty to thirty feet in length. The osteological characters presented by the remains of the Hylaeosaurus are described by Dr. Mantell as affording another example of the blending of the Crocodilian with the Lacertian type of structure; for we have, in the pectoral arch, the scapula or omoplate of a crocodile a.s.sociated with the coracoid of a lizard. Another remarkable feature in these fossils is the presence of the large angular bones or spines, which, there is reason to infer, const.i.tuted a serrated crest along the middle of the back; and the numerous small oval dermal bones which appear to have been arranged in longitudinal series along each side of the dorsal fringe.

The _Megalosaurus_, the earliest appearance of which is among the more ancient beds of the Lia.s.sic and Oolitic series, is again found at the base of the Cretaceous rocks. It was, as we have seen, an enormous lizard, borne upon slightly raised feet; its length exceeded forty feet, and in bulk it was equal to an elephant seven feet high.