Part 29 (2/2)

Pratt and Fox, in the Isle of Wight, chiefly at Binstead, near Ryde, as _Palaeotherium magnum_, _P. medium_, _P. minus_, _P. minimum_, _P. curtum_, _P. cra.s.sum_, also _Anoplotherium commune_, _A. secundarium_, _Dichobune cervinum_, and _Chaeropotamus Cuvieri_. In Hordwell cliff, also on the Hamps.h.i.+re coast, several of these species, with other quadrupeds of new genera, such as _Paloplotherium_, Owen, have been met with; and remains of a remarkable carnivorous genus, _Hyaenodon_. These fossils are accompanied by the bones of _Trionyx_, and other tortoises, and by two land snakes of the genus _Paleryx_, Owen, from 3 to 4 feet long, also a species of crocodile, and an alligator. Among other fossils collected by Lady Hastings, Sir Philip Egerton has recognized the well-known gar or bony pike of the American rivers, a ganoid fish of the genus _Lepidotus_, with its hard s.h.i.+ning scales. The sh.e.l.ls of Hordwell are similar to those of the freshwater beds of the Isle of Wight, and among them are a few specifically undistinguishable from recent testacea, as _Paludina lenta_ and _Helix labyrinthica_, the latter discovered by Mr. S. Wood, and identified with an existing N. American helix.

The white and green marls of this freshwater series in Hamps.h.i.+re, and some of the accompanying limestones, often resemble those of France in mineral character and colour in so striking a manner, as to suggest the idea that the sediment was derived from the same region, or produced contemporaneously under very similar geographical circ.u.mstances.

_Barton beds._--Both in the cliffs of Headon Hill and Hordwell, already mentioned, the freshwater series rests on a ma.s.s of pure white sand without fossils, and this is seen in Barton Cliff to overlie a marine deposit, in which 209 species of testacea have been found. More than half of these are peculiar; and, according to Mr. Prestwich, only 11 of them common to the London Clay proper, being in the proportion of only 5 per cent. On the other hand, 70 of them agree with the _calcaire grossier_ sh.e.l.ls. As this is the newest purely marine bed of the Eocene series known in England, we might have expected that some of its peculiar fossils would be found to agree with the upper Eocene strata described in the last chapter, and accordingly some identifications have been cited with testacea, both of the Berlin and Belgian strata. It is nearly a century since Brander published, in 1766, an account of the organic remains collected from these cliffs, and his excellent figures of the sh.e.l.ls then deposited in the British Museum are justly admired by conchologists for their accuracy.

_Bagshot Sands_ (2. _c_, Table, p. 197.).--These beds, consisting chiefly of siliceous sand, occupy extensive tracts round Bagshot, in Surrey, and in the New Forest, Hamps.h.i.+re. They succeed next in chronological order, and may be separated into three divisions, the upper and lower consisting of light yellow sands, and the central of dark green sands and brown clays, the whole reposing on the London clay proper.[199-A] Although the Bagshot beds are usually devoid of fossils, they contain marine sh.e.l.ls in some places, among which _Venericardia planicosta_ (see fig. 171.) is abundant, with _Turritella sulcifera_ and _Nummulites laevigatus_. (See fig. 174. p. 200.)

[Ill.u.s.tration: Fig. 171. _Venericardia planicosta_, Lamck.

_Cardita planicosta_, Deshayes.]

At Bracklesham Bay, near Chichester, in Suss.e.x, the characteristic sh.e.l.ls of this member of the Eocene series are best seen; among others, the huge _Cerithium giganteum_, so conspicuous in the calcaire grossier of Paris, where it is sometimes 2 feet in length. The volutes and cowries of this formation, as well as the lunulites and other corals, seem to favour the idea of a warm climate having prevailed, which is borne out by the discovery of a serpent _Palaeophis typhaeus_, exceeding, according to Mr.

Owen, 20 feet in length, and allied to the Boa, Python, Coluber, and Hydrus. The compressed form and diminutive size of certain caudal vertebrae indicate so much a.n.a.logy with Hydrus as to induce the Hunterian professor to p.r.o.nounce the extinct ophidian to have been marine.[199-B] He had previously combated with so much success the evidence advanced, to prove the existence in the Northern Ocean of sea-serpents in our own times, that he will not be suspected of any undue bias in contending for their former existence in the British Eocene seas. The climate, however, of the Middle Eocene period was evidently far more genial; and amongst the companions of the sea-serpent of Bracklesham was an extinct Gavial (_Gavialis Dixoni_, Owen), and numerous fish, such as now frequent the seas of warm lat.i.tudes, as the sword-fish (see fig. 172. p. 200.) and gigantic rays of the genus Miliobates. (See fig. 173.)

Out of 193 species of testacea procured from the Bagshot and Bracklesham beds in England, 126 occur in the French calcaire grossier. It was clearly, therefore, coeval with that part of the Parisian series more nearly than with any other. The _Nummulites laevigatus_ (see fig. 174.), a fossil characteristic of the lower beds of the calcaire grossier, is abundant at Bracklesham.

[Ill.u.s.tration: Fig. 172. Prolonged premaxillary bone or ”sword” of a fossil sword-fish (_Caelorhynchus_). Bracklesham. Dixon's Fossils of Suss.e.x, pl. 8.]

[Ill.u.s.tration: Fig. 173. Dental plates of _Myliobates Edwardsi_.

Bracklesham Bay. Ibid. pl. 8.]

[Ill.u.s.tration: Fig. 174. _Nummulites_ (_Nummularia_) _laevigatus._ Bracklesham. Ibid. pl. 8.

_a._ section of the nummulite.

_b._ group, with an individual showing the exterior of the sh.e.l.l.]

_London clay proper_ (3. _a_, Table, p. 197.).--This formation underlies the preceding, and consists of tenacious brown and blueish grey clay, with layers of concretions called septaria, which abound chiefly in the brown clay, and are obtained in sufficient numbers from the cliffs near Harwich, and from shoals of the Ess.e.x coast, to be used for making Roman cement. The princ.i.p.al localities of fossils in the London clay are Highgate Hill, near London, the island of Sheppey, and Bognor in Hamps.h.i.+re. Out of 133 fossil sh.e.l.ls, Mr. Prestwich found only 20 to be common to the calcaire grossier (from which 600 species have been obtained), while 33 are common to the lits coquilliers (p. 196.), in which only 200 species are known in France.

We may presume, therefore, that the London clay proper is older than the calcaire grossier. This may perhaps remove a difficulty which M. Adolphe Brongniart has experienced when comparing the Eocene Flora of the neighbourhoods of London and Paris. The fossil species of the island of Sheppey, he observes, indicate a much more tropical climate than the Eocene Flora of France, which has been derived princ.i.p.ally from the ”gypseous series.” The latter resembles the vegetation of the borders of the Mediterranean rather than that of an equatorial region.

Mr. Bowerbank, in a valuable publication on the fossil fruits and seeds of the island of Sheppey, near London, has described no less than thirteen fruits of palms of the recent type _Nipa_, now only found in the Molucca and Philippine islands. (See fig. 175.) These plants are allied to the cocoa-nut tribe on the one side, and on the other to the _Panda.n.u.s_, or screw-pine. Species of cocoa-nuts are also met with, and other kinds of palms; also three species of _Anona_, or custard-apple; cucurbitaceous fruits, also (the gourd and melon family), are in considerable abundance.

Fruits of various species of _Acacia_ are in profusion; and, although less decidedly tropical, imply a warm climate.

[Ill.u.s.tration: Fig. 175. _Nipadites ellipticus._ Bow. Fossil palm of Sheppey.]

The contiguity of land may be inferred not only from these vegetable productions, but also from the teeth and bones of crocodiles and turtles, since these creatures, as Mr. Conybeare has remarked, must have resorted to some sh.o.r.e to lay their eggs. Of turtles there were numerous species referred to extinct genera, and, for the most part, not equal in size to the largest living tropical turtles. A snake, which must have been 13 feet long, of the genus _Palaeophis_ before mentioned, has also been described by Mr. Owen from Sheppey, of a different species from that of Bracklesham. A true crocodile, also, _Crocodilus toliapicus_, and another Saurian more nearly allied to the gravial, accompany the above fossils. A bird allied to the vultures, and a quadruped of the new genus _Hyracotherium_, allied to the Hyrax, Hog, and Chaeropotamus, are also among the additions made of late years to the palaeontology of this division.

[3 Ill.u.s.trations: FOSSIL Sh.e.l.lS OF THE LONDON CLAY.

Fig. 176. _Mitra scabra_.

Fig. 177. _Rostellaria macroptera_, Sow. One-third of nat. size.

Fig. 178. _Cra.s.satella sulcata._]

The marine sh.e.l.ls of the London clay confirm the inference derivable from the plants and reptiles of a high temperature. Thus, many species of _Conus_, _Mitra_, and _Voluta_ occur, a large _Cypraea_, a very large _Rostellaria_, and sh.e.l.ls of the genera _Terebellum_, _Cancellaria_, _Cra.s.satella_, and others, with four or more species of _Nautilus_ (see fig. 182.) and other cephalopoda of extinct genera, one of the most remarkable of which is the _Belosepia_.[202-A] (See fig. 183.)

[Ill.u.s.tration: Fig. 179. _Nautilus centralis._]

[Ill.u.s.tration: Fig. 180. _Voluta athleta._]

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