[630] Owen’s Odontography, p. 271, which should be consulted for more minute details.
[631] To fully comprehend the minute structure of these and the other teeth figured in [Pl. VI.] Professor Owen’s plates should be examined; the small scale necessarily adopted in the present work rendering it impossible to do justice to the subject.
Four specimens of the sacrum, composed of five anchylosed vertebral (Foss. Til. For. pl. xix. fig. 12), have been discovered; one of these is from Tilgate Forest. The femur of the Megalosaurus has two large rounded trochanters of nearly equal size, below the head of the bone; its shaft is sub-cylindrical, and slightly bowed.
This colossal carnivorous Saurian, whose length is estimated at thirty feet, appears to have been terrestrial, and an inhabitant of the same terra incognita as the Iguanodon; it probably preyed on the smaller reptiles, and the young of the Iguanodon, Crocodilians, &c.
Hylæosaurus (Wealden lizard) Owenii. Wond. pl. iv. and p. 435; Geol. S. E. pl. v.—In the summer of 1832, I obtained the interesting specimen which first demonstrated the existence of the remains of another extraordinary modification of Saurian organization in the Wealden. The circumstances which led to this discovery afford an instructive lesson to the young collector.
Upon visiting a quarry in Tilgate Forest, which had yielded many organic remains, I perceived in some fragments of a large mass of stone, which had recently been broken up and thrown on the road-side, traces of numerous pieces of bone. I therefore collected all the recognisable portions of the block, and had them conveyed to my residence. The first step was to cement together those pieces that would admit of juxtaposition, and these were at length united into a block of stone five feet long, three wide, and about one foot thick. This was firmly fixed in a stout frame, to prevent the separation of the united portions during the process of chiselling. Guided by the indications which the sections visible on the edge afforded, a thin iron wedge was carefully driven in, about half an inch above the uppermost layer of bones, and a large slab was flaked off; the three dermal spines (Wond. pl. iv. 5) in the middle of the specimen were thus exposed, and shivered to pieces; some fragments adhered to the mass broken off, others to the block, and many were detached; every piece, however small, was collected, and those adhering to the slab were chiselled out; and the whole were then carefully replaced and cemented to the bones that remained imbedded in the large block. After an interval of some days, to allow of the firm cohesion of the cemented parts, the task was resumed, and the stone chiselled away, until some portion of the large bones of the pectoral arch (Wond. pl. iv. 7) were observed. The specimen was at length brought to the state in which it now appears (in the British Museum[632]); but during the progress of its development, which occupied many weeks, it was repeatedly necessary to suspend the work, and unite displaced fragments of bone, and resume the task after their consolidation. The plate in the Geol. S. E. conveys a good idea of the original.
[632] See Fossils, Brit. Mus. p. 139, &c.
The specimen consists of a part of the spinal column, composed of seven dorsal and three or four cervical vertebræ, almost in their natural juxtaposition, with obscure indications of a part of the base of the skull; eleven ribs; the bones of the pectoral arch (two coracoids and two scapulæ); with numerous dermal bones and spines. A second specimen of this reptile was found near Bolney, in Sussex; and like the former, it was, unfortunately, almost wholly destroyed by the labourers; but I obtained many bones, some of which are perfect, and indicate an animal of considerable magnitude: a scapula, nineteen inches long, an arm-bone or humerus, numerous ribs, bones of the phalanges, &c. A fine series of twenty-six caudal vertebra, having a total length of nearly six feet, with chevron bones and dermal spines, was discovered in 1837, in Tilgate Forest.[633] A few detached bones are the only other relics of this reptile that have come under my observation.[634] The osteological characters presented by these remains afford another example of tire blending of the Crocodilian with the Lacertian type of structure; for we have in the pectoral arch the scapula or omoplate of a crocodile associated with the coracoid of a lizard. Another remarkable feature in these fossils is the presence of the large angular bones or spines (described p. 660, figured [Lign. 208]), which, there is reason to infer, constituted 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. (Geol. S. E. p. 323.)
[633] See Fossils, Brit. Mus. p. 323.