26. ORGANIC REMAINS OF THE JURASSIC SYSTEM.The fossils discovered in the Oolitic and Liassic strata amount to many hundred species,* and it is impossible in a work of this nature to give but the briefest summary of these organic remains; it must suffice to offer a few general remarks on the nature of the fauna and flora of the sea and land during the vast period of time which the accumulation of sediments of such extent and thickness must have required.

Vegetable remains. Some species of fucoidal plants and upwards of a hundred species of terrestrial vegetables have been determined from the Jurassic rocks of Britain. The latter consist of ferns, cycadaceous plants, and coniferous trees; constituting a flora analogous to that which now prevails in the maritime districts of the West Indies, New Holland, and the Cape of Good Hope, &c. A large species of plant allied to the recent Marestail (Equisetites columnaris) is abundant in the coal-bearing Oolite; and in Yorkshire so many of these plants occur in an erect position that it is supposed they must have grown on the spots they now occupy: we shall recur to this fact hereafter.

One of the most remarkable fossil vegetables discovered in this formation in England is the fruit of a tree (Podocarya Bucklandi, Unger) allied to the Pandanus or Screwpine, from the lower Oolite of Charmouth in Dorsetshire.†

Fragments of trunks of coniferous trees of the Araucarian type are found throughout the Jurassic formation; and, as we have already stated, the last bed of the Oolite, when

The student is referred to Prof. Phillips' tables of fossils in the Encyclopædia Metrop., art. Geology, to Sir H. De la Beche's Manual of Geology, and to Mr. Morris's British Fossils, for lists of the fossils found in the British Oolite and Lias; and to the beautiful work on the organic remains of the "Terrains Jurassiques," by M. D'Orbigny. See also Medals of Creation.

† Dr. Buckland's Bridgwater Treatise, vol. ii. pl. 63.

elevated above the waters, was clothed with pine-forests (vol. i. 400).

The quantity of drift-wood in a carbonized state, but not converted into coal, is very considerable in the argillaceous strata. In the Oxford-clay, at Trowbridge,* masses of wood occur in abundance; oysters, terebratulæ, and other shells are often adherent to the fragments of trunks and branches of trees, which have evidently been drifted from a distance into the bed of the sea. Much of this wood is soft and flexible when first exposed, and, when dry, burns with a bright flame. In the Lias of Whitby, Lyme Regis, and other localities, the wood is often calcareous, and admits of a fine polish occasionally silicified masses are met with.t

27. ZOOPHYTA AND RADIARIA.-Of corals and moss-corals numerous jurassic species abound. The reefs of coral constituting the Coral-rag have already been alluded to. In some parts of Germany coralline Oolites are largely developed, and all the corals are silicified in certain localities; this is especially the case between Nattheim and Heidenheim, whence exquisite specimens of Astræa, Lithodendron, &c. have been obtained.

In the beds of chert in the Oolite of Tisbury in Wilts, shells and corals are found in a beautifully silicified state, particularly a species of Isastraa (I. Tisburiensis). Large silicified masses of this coral are met with, which, on being cut and polished, display the intimate structure of the original, and form an ornamental material for the jewellers and lapidaries. A matchless specimen of the soft parts of a Trigonia, transmuted into silex, was obtained from Tisbury by the late Miss E. Benett, and is now, with the greater

*See above, p. 500.

Beautiful specimens of the fossil wood and plants from the Lias and Oolite are exhibited in the British Museum. Petrifact. Chap. I. Geol. Soc. Journ. vol. vii. part 2, p. 71.

part of the collection of that lady, in the possession of Mr. Wilson of Philadelphia.*

The Crinoidea, or lily-shaped animals, are also abundant, and are often found in an admirable state of perfection. Whole slabs of many of the Lias-shales are covered with Pentacrinites, frosted with brilliant pyrites, and lying in relief on the stone, as if spread out on the sea-sand.†

Of the Echinoidea upwards of seventy species, and of Star-fishes nearly twenty genera, comprising many species, have been determined from the British Oolites.‡ Some splendid Star-fishes from the Yorkshire Oolite and Lias are

figured in Charlesworth's London Geological Journal, pl. 17 (Astropecten arenicola), and pl. 19, 20 (Ophiodermata).

28. MOLLUSCA. - The sheils, both of testaceous and conchiferous moliuscs, amount to many hundred species. Of the Cephalopoda, as Nautili, Ammonites, Belemnites, &c., several hundred species, belonging to numer

ous genera, have been figured and described.§

The state of perfection in which the animals allied to the Cuttle-fish occur in the Lias, and also in the clays of the

* Figures and a description of this extraordinary British fossil have been given by Mr. Charlesworth in the London Geological Journal. + See Petrifactions, &c., p. 88.

Dr. Wright's Monograph, published by the Palæontographical Society, 1856, furnishes a careful and lucid history of the Jurassic Echinoderms of Britain.

to.

See Sowerby's Mineral Conchology, and the works before referred

Oolite, especially in the Oxford-clay of Wiltshire,* is most extraordinary. The soft part of the body and arms, the capsule of the globe of the eye, and the ink-bag still retaining its inspissated secretion, are often found in their natural position, and distinctly recognisable. This state indicates a rapid imbedding of the animals while in their natural element.†

29. CRUSTACEANS AND INSECTS.-Numerous genera of Crustaceans and Insects have been collected from the Jurassic deposits: the museum of the late Count Münster was celebrated throughout Europe for the magnificent series of remains of this kind which it contained.

Species allied to the Shrimps, Prawns, Lobsters, and Crabs have been found in great perfection at Solenhofen, Pappenheim, &c.; an extinct form (Eryon Cuvieri‡), and some Limuli,§ occur in an exceedingly perfect state; and small bivalved Entomostraca are not rare in some beds, though as yet they are undescribed.

A fine fossil Dragon-fly, from Solenhofen, in the cabinet of the Marquess of Northampton, is figured in Medals of Creation (vol. ii. p. 551). In England, the Coal-measures, Lias, Stonesfield-slate, Forest-marble, and Wealden have yielded fossil insects. Among the specimens found in the Lias, is a wing of a very large Dragon-fly, which closely resembles the recent species in the general arrangement of the nervures, and appears not to be separable from the genus Eshna (Lign. 127). In this fossil an opaque spot (a) exists on the anterior margin of the wing, as in most of the living Libellulidæ.

Mr. Brodie has figured and described numerous fossil insects from the Oolite and Lias of England, comprising

* See the London Geological and Palæontological Journal, No. 2, Pl. XV. XVI., for figures of some remarkable specimens in the late Mr. Channing Pearce's cabinet.

+ See Dr. Buckland's Bridgwater Treatise, for exquisite figures of the shells and soft parts of Cephalopoda.

Medals, ii. p. 520.

§ Ibid. p. 522.

History of Fossil Insects (1845), p. xiv. In this work will be found

Coleoptera, Neuroptera, Hemiptera, and Homoptera. The wings of insects allied to the recent genus Panorpa have been found in the Lias of Wainlode Cliff, on the banks of the Severn.*

LIGN. 127.-FOSSIT WING OF A SPECIES OF DRAGON-FLY; FROM THE LIAS OF BIDFORD, WARWICKSHIRE. (Nat. size.)

(Eshna Liassina, of Mr. Strickland †)

The several hundred specimens of fossil insects that have been discovered in the Lias belong nearly all to forms that inhabit temperate climates, and present a remarkable affinity to existing families; so that in one instance only has Mr. Westwood, the distinguished entomologist, ventured to propose a new generic name. The same fact of the close relationship of the fossil to the recent types of Insecta holds good, with but one or two exceptions, in the case of the insects from the Purbeck beds.

30. FISHES.-All the Fishes of the Oolite are referable to extinct genera, and essentially differ, as a whole, from those

an account of the localities in which insect-remains had been at that time discovered in the secondary rocks of England. See also Dr. Buckland's Bridg. Treatise; and Medals of Creation, vol. ii. p. 547, &c.

See Medals of Creation, vol. ii. p. 553.

Mag. Nat. Hist. vol. iv. p. 301. See Nova Acta Car. Leop. Acad. vol. xix. part 1, for Germar's fossil Insects from Solenhofen.

Mr. Strickland, on the results of recent researches into the fossil insects of the secondary formations of Britain: Brit. Assoc. Reports for 1845, p. 58.