the country of the iguanodon, and have constituted an important feature in its flora. It is with great pleasure that I record my sense of the high value of the researches of Dr. Dunker, of Hesse Cassel, the diligent and successful explorer of the Wealden of North Germany, by naming this species of fossil cone, Abietites Dunkeri.* Several fragments of stems of clathraria and endogenites have been obtained from Sandown Bay, but they afford no additional information respecting the structure of the original plants. § 19. WEALDEN REPTILES (ante, p. 225).—So numerous and gigantic are the specimens obtained by myself and others in the course of the last two years, that the account given in a previous chapter of the abundance and magnitude of the reptilian remains washed out of the cliffs along the southern shores of the Island by the continual encroachments of the sea, so far from being an exaggerated statement, as some authors have supposed, conveys but a faint idea of the numbers and colossal proportions of * There are now at least six well-defined species of coniferous fruits that may be referred to the British Wealden and cretaceous flora, viz. Abietites a Benstedi, mihi, greensand, with iguanodon remains, Dunkeri, mihi, Wealden of Isle of Wight. Pinites Fittoni, mihi, Wealden of Tilgate Forest.b Sussexiensis, mihi, greensand of Sussex. Zamites crassus, Lindley, Wealden of Isle of Wight. a The provisional generic term, Abietites, is adopted in conformity with the nomenclature of M. Göppert. b This remarkable cone, (figured and described by Dr. Fitton, Geol. Trans. vol. iv. Pl. XXII. fig. 10,) which is characterised by the double prominences on the scales, is probably more nearly allied to pinus than to abies. It will be convenient to affix a specific name, and I propose that of Fittoni, as a tribute of respect justly due to one of the most eminent British Geologists. WEALDEN REPTILES. 331 the bones of terrestrial and aquatic saurians contained in the Wealden deposits. To particularise only those in my possession would require more space than the limits of this volume will admit, and it must suffice to mention that since my former description of the known bones of the skeleton of the iguanodon, there have been discovered fine specimens of the humerus, femur, tibia, several cervical, dorsal, and caudal vertebræ, proximal metatarsals and ungueals, portions of two lower jaws, and a fragment of the upper jaw with seven teeth in their natural position. One of the most interesting specimens I have seen is from Brixton Bay; * it consists of a considerable part of the spine of a very young iguanodon imbedded in a block of white sandstone, the bones being, as usual, of a dark colour, from an impregnation of iron. There are thirteen or fourteen dorsal vertebræ in a continued series, and although most of these bones are destitute of the neural arch and lateral processes, yet a good idea of the structure of that part of the vertebral column is presented. There are three or four cervical vertebræ detached from the block: and portions of several ribs, some of which lie upon a thin black substance, with a shagreen surface, apparently the remains of the dermal integuments. considerable number of the phalangeal and metatarsal bones of the left foot are imbedded in close apposition, the plantar aspect lying uppermost, and though much crushed, their agreement with the corresponding parts in the Maidstone iguanodon, and other adult examples, is very obvious. There are also several other bones, some of which are probably tarsals, but these are too obscured by the investing sandstone to admit of definition in the present state of the specimen. A * Now in the possession of J. S. Bowerbank, Esq., to whom I am indebted for the loan of it. Of several large reptiles, whose aquatic, and probably marine, habits, may be safely inferred from the characters of the bones of the extremities, there are in my possession vertebræ, and phalangeal and ungueal bones, that probably belong to the genus cetiosaurus; yet there is some difficulty even in determining the generic relations of these remains, for there are several anchylosed vertebræ, apparently portions of a sacrum of the dinosaurian type, which unquestionably belong to the same individual as the so-named cetiosaurian vertebræ. A scapula, 26 inches long, and 12 inches wide, found with several enormous vertebræ, and portions of two anchylosed bones, apparently the radius and ulna, bear much resemblance to those of the dugong; the extreme solidity of the bones of the fore-arm, with the absence of a medullary cavity, at once distinguishes them from those of the terrestrial saurians with which they are associated. From the essential difference existing in the characters of certain convexo-concave vertebræ lately obtained, it is evident that this modification of the bones composing the anterior part of the spinal column was not, as some eminent authors have supposed, restricted to one genus,* but existed in several genera of the extinct saurians of the Wealden. It is not a little remarkable that no teeth have been found that can be assigned to these colossal animals; those of the iguanodon, megalosaurus, and hylœosaurus, and the common crocodilian type, as goniopholis, teleosaurus, suchosaurus, &c., are the only forms I have procured, or have recognised in the collections of my scientific friends. It is highly probable that some modification of the conical, striated, vertically successional teeth, so prevalent a form in the crocodilian reptiles of the oolite, may have characterised the dental organs of some of the imperfectly known gigantic saurians of the Wealden; at present I am not *Streptospondylus, of H. Von Meyer. FOSSILS OF THE PURBECK STRATA. 333 aware of any teeth even of this type that can be referred to them; the discovery of teeth and jaws with other parts of the skeleton, can alone afford a solution of the problem. § 20. PURBECK STRATA (ante, p. 255).-On the palæontological characters of the strata composing the lowermost series of the Wealden formation-the Purbeck -an interesting memoir was communicated a short time since to the British Association at Edinburgh by Professor Edward Forbes, of which the following is an abstract The strata examined were those exposed along the coast from Swanage to Weymouth. Professor Forbes conceives that the Purbeck series may be divided into three natural groups, each with its peculiar assemblage of organic remains, and that the lines of demarcation between them are not the result of physical or mineral change in the deposits. The lithological features which attract the eye, such as the dirtbeds, the dislocated strata at Lulworth, and the cinder-bed, do not indicate any breaks in the distribution of organised beings. The causes which led to a complete change in the organic forms three times during the deposition of these freshwater and brackish strata must be sought for, not simply in a rapid or sudden change of their area into sea or land, but in the great lapse of time which intervened between the periods of their deposition. A most remarkable feature in the molluscous fauna of the Purbeck is the similarity between the generic forms and those of tertiary freshwater strata, and existing genera; and this resemblance is so great, that had we only such fossils before us, and no evidence of the position of the rocks in which they occur, we should be wholly unable to assign them a definite geological epoch. From a comparison of the fossils with those collected from the Hastings sands and Weald clays, Professor Forbes considers the fauna of the middle and *The result of an examination of the Purbeck coast during a residence at Swanage in the course of the summer of 1850. upper Wealden series as entirely distinct, so far as species of mollusca are concerned, from those of the lower or Purbeck division. Some of the species reputed identical prove to be distinct; and others are derived from certain strata near Tunbridge, which Professor Forbes supposes may belong to the Purbeck.* This he conceives to be confirmed by the Wealden of the north of Germany, the fauna of the upper part of which corresponds with our Wealden, and that of the lower series with the Purbeck. But the most extraordinary fact described in this communication is, that the Purbeck freshwater mollusca and cyprides differ less from living British species than the latter do from those of other countries. Professor Forbes has collected between fifty and sixty species of mollusca in addition to those previously described; among them are species of physa, planorbis, and limneus, that cannot be distinguished from living forms; and with them were associated fossil seed-vessels of charæ (gyrogonites). § 21. RETROSPECTIVE SUMMARY.-The facts described in the preceding pages of this supplement corroborate the general inferences enunciated in a previous chapter (ante, p. 293), and are highly interesting and suggestive. The fauna and flora of the eocene strata have been enriched by several species already known in the equivalent deposits of other countries, but which have only recently been discovered in the Isle of Wight, and the adjacent parts of Hampshire. Palms and club-mosses (lycopodia) are added to the fossil plants, and new species of chelonians, crocodiles, and serpents to the reptiles. The remarkable carnivorous animal, the hyænodon-previously observed only in the eocene formation of France-and three new genera of pachyderms, allied to the palæotherium and * There does not appear to me any satisfactory proof that this supposition is correct. |