J3S 



MEOAUlPHUa 



MEOALOSAURUa 



736 



which is wide at the bue, and sometime* inflected ; eye* very large, 

 supported on a very abort peduncle; abdomen narrow, extended, 

 linear, composed of wren joints, of which the fire intermediate onei 

 are provided with appendage*, namely, the four first with false feet, 

 baring their external division very large and ciliated, and the fifth, 

 on each aide, with a horizontal blade or lamina, which is oral and 

 ciliated, composing, with the last joint, a sort of fin, differing a little 

 from that of the other .Vacrura. 



If. mulica differs from the other species in baring the rostrum a 

 little inflected perpendicularly on the carapace and canaliculated in 

 the middle; also in the absence of a recurred spine on the haunches 

 of all the feet The shell is truncated posteriorly, and has no point 

 like that of M. armala. Colour brownish. 



It was found by Messrs. Audouin and Adolphe Brongniart at the 

 mouth of the Loire. 



mntica. 

 , magnified ; , Internal antenna ; e, external antenna ; rf, natural ilse. 



MEGALOPHUS. [MusciciPiD*.] 



MEOALOSA'URUS, the name assigned by Dr. Buckland and the 

 Rev. W. Conybeare to an extinct genus of Sauri.ins found in the 

 Oolitic Slate at Stonesfield, near Woodstock, and other localities. 



Though no entire skeleton has yet been discovered, the number of 

 bones and teeth collected give sufficient data to enable the observer to 

 pronounce upon the general osseous structure, with almost aa great a 

 certainty as would be the result of the examination of the bones of 

 the animal in a perfect and connected state. 



The femur, or thigh-bone, and tibia, or leg-bone, are nearly three 

 feet in length severally, so that the entire hind-leg must have been 

 nearly two yards long, and the discovery of a metatarsal bone mea- 

 suring 13 inches indicates that the foot was of a corresponding length. 

 From these and other remains, including the vertebra;, teeth, Ac., the 

 size of this gigantic saurian has been calculated and its habits 

 ascertained. * 



"The most important part of the Megalotaurut yet found," observes 

 Dr. Buckland, in his ' Bridgewater Treatise/ " consists of a fragment 

 of the lower jaw, containing many teeth." 



Antrilor extremity of right lover jaw of Uegntoiaurut, ham Monciflrld, one- 

 fourth Mtarti lice. 



a, Tlew of the Inside j b, rlcw of the outside. Buckland. 



"The form of this jaw shows that the head wan terminated by a 

 straight and narrow snout, compressed laterally like that of the J>el- 

 jJiinut ftangttictu." 



The structure of these teeth [Fcuo*] leares no doubt as to the 

 carnivorous habits of this immense extinct lizard ; and the internal 

 structure of the cylindrical and other bones shows that is was a terres- 



trial animal, though it may hare occasionally taken to the water in 

 pursuit of prey, such as Pletiotauri and fishes. Its ordinary food is 

 supposed to hare been the smaller reptile*, crocodile*, and tortoises, 

 whose remains occur abundantly in the strata where those of 

 Mrgalotaurut abound. 



The form of the teeth too exhibits a combination of mechanical 

 contrivances extremely remarkable; and there is a provision for a 

 constant succession of new teeth to. supply the loss of the old one*. 

 For this purpose the new teeth are formed in distinct cavities by the 

 side of the old ones, and towards the interior surface of the jaw ; so 

 that each as it grew gradually pushed away the one previously existing 

 there, expelling it by the usual process of absorption, and insinuating 

 itself into the cavity thus left vacant When young, and first pro- 

 truding above the gum, the apex of the tooth presented a double 

 cutting edge of serrated enamel ; but as it adranced in growth its 

 direction was turned backwards in the form of a pruning-knife, and 

 the enamelled sawing edge was continued downwards to the base of 

 the inner and cutting side, but became thicker on the other side, 

 obtaining additional strength when it was no longer needed as a 

 cutting instrument. 



Tooth of Uegaloiaurui, two-thirds natural size. The' dotted lines Indicate 

 the compressed conical cavity, containing pulp, within the root of the growing 

 tooth. 



a, transverse section of the same, showing the manner in which the back and 

 sides arc enlarged, and rounded In order to give strength, and the front Is 

 brought to a strong and thin cutting edge. 



The vertebra of the Megaloaaurui indicate a more decided departure 

 from the Lacertian type than the mode of dentition ; but by far the 

 most remarkable difference occurs in the group of fire of these bones, 

 which anchylosed together form the sacrum, and which are so charac- 

 teristic of the Land Saurians. Up to the time indeed that these bones 

 were discovered, there had been no instance recorded of any reptilian 

 animal possessing more than two sacral vertebrae ; and when first the 

 megalosaurian remains were described by Dr. Buckland, three of the 

 five were referred to by him as belonging either to the lumbar or caudal 

 series. The whole five however properly belong to the sacrum, and 

 they were so contrived as to give an amount of strength and resisting 

 power that must have corresponded to enormous muscular energy and 

 weight; and, as if to give them every possible advantage of position, 

 they are not anchylosed in a straight line, but in a gentle curve, form- 

 ing an arch, and therefore still better able to support the weight 

 pressing upon them. All the bones of the extremities are exceedingly 

 large compared with the same parts in existing Saurians; and the 

 cylindrical ones are hollow, like those of land animals. The thigh-bone 

 and the tibia each measure nearly three feet in length ; and thus the 

 contour of the hinder part of the body, raised high abore the ground, 

 must have been totally unlike that of any existing crocodilean ; and 

 the large share in the support of the trunk assigned to the hinder legs 

 of the Mtgaloiaunu probably made it necessary in that genus, as in 

 the heavy land quadrupeds, that a greater proportion of the spine 

 should be permanently and solidly fastened together, in order to 

 transfer the weight through the bones of the pelvis to the legs. 



The existence of the bones of the foot measuring" 13 inches long, is 

 also a sufficient proof that a proportionately large base was prepared 

 for the immense column which the leg would form. Several bones of 

 the anterior extremity have also been referred some of them not 

 without doubt to this singular genus ; and its dimensions have been 

 calculated rather with reference to these than to the general anatomy 

 of the animal. 



This mode of calculation has however been objected to by Professor 

 Owen, and with great reason ; for it is in the highest degree impro- 

 bable, that in an animal raised six or eight feet from the ground there 

 should be a tail as long in proportion to the body as that of existing 

 lizard*. To obtain a correct idea of the probable dimensions it is 

 certainly safest to calculate by the length of the vcrtebnc and their 

 probable number, and in that way we shall arrive at the OMOraaian 

 that the body may bare attained a length of 12 feet; and that 

 assuming it had a* many vertebra as the crocodile, which is perhaps 



