WEALDEN FORMATIONS. 13 



scribed and referred to the Megalosaurus by Dr. Buckland.* It is remarkable, like the 

 corresponding ribs of the Iguanodon,f for the length and strength of the part between 

 the head, c, and tubercle, t, called the "neck;" but this presents a different form in 

 transverse section, and a different direction from the neck of the rib in the Iguanodon. 

 The outer border of the body of the rib does not expand below the tubercle, t, to form 

 the shield-like plate which characterises the larger ribs of the Iguanodon ;j the entire 

 body of the rib is more slender, or narrower, but is, perhaps, stronger, from being less 

 flattened and more quadrate, in transverse section ; it is strengthened by two low 

 lateral ridges. The relative thickness of the dense, compact outer wall of the rib, to 

 the more open cancellous structure of the central part, which forms what might almost 

 be termed a medullary cavity, near the middle of the body of the rib ; and the form of 

 the transverse section of the cervix and body of the rib, are shown in T. IV, fig. 3. 



Cuvier, in his explanation of the figures introduced into the ' Ossemens Fossiles,' 

 from the original Memoir of Buckland, describes three of the ribs, in the fourth 

 edition (8vo, p. 93) as belonging to " un saurien voisin des crocodiles." It is, in fact, 

 only in the Crocodilian order amongst existing reptiles, that the ribs present a head, 

 neck, and tubercle, coincident with that two-fold articulation with the rest of the 

 vertebra which is associated in the Crocodiles and Gavials with a higher grade of 

 structure of both heart and lungs. The ribs, however, found associated with other 

 parts of the skeleton, including a tooth of the Iguanodon, in the Maidstone quarry of 

 Kentish rag-stone,§ demonstrated that the Crocodilian type of rib was associated with 

 the Dinosaurian modifications of sacrum and limbs in that gigantic reptile : and there 

 can be no reasonable doubt that the like association characterises the skeleton of the 

 Megalosaurus. The minor modifications, above specified, of the huge ribs and frag- 

 ments of ribs found with portions of jaw, limb-bones, and complex sacrum of answer- 

 able magnitude, in the same Oolitic stratum in Oxfordshire relate only to the generic 

 distinctions of the Megalosaurus, as compared with the Iguanodon. 



The scapula. Tab. V. 



In the Wealden deposits at Stammerham, Sussex, a scapula of the Dinosaurian 

 type, but differing from the known scapulse of the Iguanodon and Hylseosaurus, has 

 been discovered by G. B. Holmes, Esq., of the neighbouring town of Horsham, by 

 whom I have been favoured with the drawing lithographed in T. V. 



As remains of the Megalosaurus have been obtained from the same locality, some of 



* Tom. cit., pi. 43, fig. 1. 



f Palseontograpbical Society, 'Monograph of Wealden Reptiles,' No. 2, 1854, Tab. II. 



% Tab. cit., figs. 1 and 2. 



§ ' Palseontographical Memoirs,' 1851, Tab. 



