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ON VISUAL EDUCATION AS APPLIED TO GEOLOGY. 



[1854, 



The science of Palaeontology, or as the literal translation of 

 the name indicates, the study of ancient beings, treats of the 

 history of fossils ; and its principal end is to make known the 

 forms and the zoological relations of the beings which have in- 

 habited the globe at divers epochs anterior to our own. It 

 has also to fill one of the most remarkable pages in the history 

 of the earth, by retracing the successive phases of the organi- 

 zation of the animals that have peopled it. It has two principal 

 applications— --1st, to Zoology, by making known those new or 

 rather unknown forms and conditions of existence which are 

 often wanting in living nature. It may sometimes, by offering 

 new transitions, demonstrate natural relations of which we were 

 ignorant ; it re-acts also upon the general laws of comparative 

 anatomy, and has contributed much to its researches and 

 discoveries, and it is connected with all the questions relative 

 to the origin and development of organized beings. 2dly, to 

 Geology — ^Palseontology again applies to geology, by furnishing 

 the only certain basis for the determination of the stratified 

 earths, and by clearing up several essential points relative to 

 the ancient limits of seas and continents. The study of fossils 

 is destined to throw a great light upon the determination of the 

 order of succession of the beds or strata, and of their relative 

 age. The study of fossils may, also enlighten questions of 

 detail. Certain sorts of fish and of mollusca are known to be 

 essentially belonging to rivers, and others to inhabit the seas. 

 If the fossils of an earth belong to the fresh water species, we 

 may legitimately conclude that such earth has been deposited 

 by rivers or by lakes of fresh water. If, on the contrary, the 

 beings that have there left their remains belong to the marine 

 species, it may be presumed that such deposit owes its origin 

 to the waters of the sea. 



In latter years fossils have revealed remarkable facts con- 

 cerning the state of the globe at various epochs. Some authors 

 have sought to make use of them to define the shores and the 

 configuration of the ancient seas ; at le&st, we know that in the 

 deep sea we find fewer molluscs than near the coasts : the depth 

 and absence of vegetation cause the greatest part of the species 

 to avoid the centre of the seas ; the shores, on the contrary, 

 which furnish a more abundant nourishment, and the rocks 

 near the surface, serve as shelter to a much larger number of 

 individuals. The presence of numerous fossils, and, above all, 

 that of species which belong to the kinds essentially fluviatile, 

 may then serve to indicate the shore of ancient seas, whilst 

 rare fossils of species from the deep seas prove, on the contrary, 

 that the earths where they are deposited have been formed far 

 from the coasts of seas at divers epochs. Thus it will be seen 

 that geology would be but a barren study without some know- 

 ledge of the fossil remains of those beings who apparently first 

 peopled the waters of the earth. 



An inspection of the various strata in which fossil remains 

 have been deposited serves to prove that, in general, a constant 

 order has existed in their formation. The sea, by which the 

 entire earth appears to have been covered, having rested in 

 certain situations a sufiicient length of time to collect particular 

 substances, and to sustain the life of certain genera and species 

 of animals, has been afterwards replaced by another sea, which 

 has collected other substances, and nourished other animals, 

 whose remains are found in each stratum, and are generally 

 limited to one formation, or, if reappearing in a successive 

 stratum, much modified in size or stmcture. I have pre- 

 pared here a diagram, which will give you an idea of the 

 succession of epochs ; each epoch containing a succession of 

 periods and formations, which, though often found to have been 



disturbed by some vast convulsive force, can yet be retraced to 

 its natural order of succession and super-position. 



The diagram shews those formations which constitute 

 the secondary epoch, or, if described in ascending order^ 

 the commencement of that vertebrate existence which left une- 

 quivocal evidence of its inhabiting the earth, by leaving the 

 Imprint of its footmarks, which, at one time, was all we knew 

 of the extraordinary inhabitants of the New Red Sandstone,' 

 when it was called Chirotherium, from the hand-like shape of 

 the foot-marks, until the mighty genius of Professor Owen 

 placed the teeth and head before us, with such Indisputable cha- 

 racters as united them to the footmarks, and thus, by Induction, 

 the whole animal was presented to us. 



Next, in ascending succession, we have tho Tethyosaurus, 

 Platyodon, Tentilrostrls, and Cummunis, the Plesiosaurus 

 Dolichodirus, as restored by Dean Conybeare, the Plesiosaurus 

 Macrocephalns and Hawklnsii, the latter named by Professor 

 Owen after Mr. Thomas Hawkins, who with great enthusiasm 

 cleared it from its matrix of Lias, and made the first great col- 

 lection of fossils of the Lias which were purchased by the trus- 

 tees of the British Museum, where they are now, and form the 

 most striking features of the national collections of fossils. 



It next illustrates the upper portion of the Lias, sometimes 

 known as the alum shale, so well developed at Whitby, in 

 which remains of the Teleosaurus have been so frequently 

 found. This animal will be recognised by its near resemblance 

 to the crocodile of the Ganges called Gavial, or Garrial, as it 

 should be called : to the casual observer the principal difference 

 consists In its greater size. The next formation above the Lias 

 is the Oolite, of which at present that singular reptile, the 

 Pterodactyle, represents the inhabitants, while the intermediate 

 formation, called the Stonesfield slate, bears the great discovery 

 of Buckland, the Megalosaunis, or the great lizard. This, the 

 upward strata of the great Oolite, brings us to the formation 

 called the Wealden, which Professor Owen, in one of his elabo- 

 rate descriptions of the British fossil reptiles, calls the metropolis 

 of the Dinosaurian order, which I have here represented by the 

 best known and most typical species, the Hyljesaurus or lizai'd 

 of the mud, with its extraordinary dermal covering and long 

 range of dorsal scutes, of which the bones were found by the 

 late Dr. Mantell, whose persevering researches in Wealden 

 formations first gave the idea to science of the former existence 

 of the Iguanodon. 



These restorations of the Iguanodon I made fi-om the mea- 

 surements of the great Horsham specimen, as the largest is 

 called, from its having been found and carefully preserved by 

 Mr. Holmes, surgeon, at Horsham, who has bestowed much 

 care and attention on the development of the great fossils found 

 In his neighbourhood, among which are the largest known 

 specimens of the bones of Iguanodon, having also the greater 

 value of being found altogether, evidently belonging to one in- 

 dividual. These he kindly placed at my service for comparison 

 with the better known Maidstone specimen now In the British 

 Museum, which was so admirably extricated from its matrix 

 and preserved by Mr. Beusted. 



This Iguanodon was the animal the mould of which I con- 

 verted into a saUe a manger, and in which I had the honour 

 of receiving Professor Owen, Professor E. Forbes, and twenty 

 of my scientific friends to dinner on the last day of the year 

 1853. This circumstance will best Illustrate the great size 

 of these animals, the restoration of which has involved some 

 of the greatest mechanical difficulties that can come within 



