16 FOSSIL REPTILIA OF THE 



The clavicle. Tab. IV, fig. 4. 



A slender sigmoid bone, nearly two feet in length, from the Stonesfield slate, now 

 in the Geological Museum at Oxford, T. IV, fig. 4, was referred, by the discoverer of 

 the Megalosaurus, to that species,* from its resemblance to the clavicle in certain 

 Lizards, especially, as Cuvier remarks, who concurs in this determination with 

 Buckland, to the clavicle of the great scincoid Lizard.f It is, however, less bent upon 

 itself than in that existing Saurian, and bears a closer resemblance to the clavicle of 

 the Iguanodon.% The more expanded median or pectoral extremity of the bone in 

 question has one margin fractured, that which corresponds with the margin from which 

 the two processes are developed in the clavicle of the Iguanodon : how far, therefore, 

 the Megalosaurus resembled the Iguanodon in the form or even existence of those 

 processes cannot at present be determined. The shaft of the clavicle presents a 

 similar gentle sigmoid curve, but is relatively thicker and more bent than in the 

 Iguanodon ; its transverse section is subtrihedral : the outer or scapular end is more 

 expanded ; the sternal end is more rounded or convex. With respect to the present 

 bone, Cuvier has remarked that according to the proportions of the clavicle in existing 

 Lizards, it bespeaks an animal nearly sixty feet in length, § but the proportions of the 

 trunk to the limb-bones alter with the increasing bulk in different species of the same 

 family or order, and we shall presently show that there are surer grounds for arriving 

 at the true bulk of the Megalosaurus, than the comparison of its limb-bones with those 

 the small existing Lizards affords. 



The ischium. Tab. IV, fig. 5. 



The subcompressed, three-sided bone, flattened and expanded at one end, thickened 

 and less expanded at the opposite end, which formed part of a large cotyloid cavity, 

 has most claims to be regarded as the ischium of the Megalosaurus. This bone, now 

 in the Geological Museum at Oxford, formed part of the original series obtained from 

 the Oolitic slate at Stonesfield, and described by Dr. Buckland. || 



The longest diameter of the bone is 18 inches; the breadth of the almost straight, 

 thin, mesial border, is about 14 inches, but the angles are somewhat mutilated ; the 

 narrow even flattened surface of this border appears to have joined, probably with 

 some interposed fibro-cartilaginous matter, to the corresponding margin of the opposite 

 ischium. 



* Buckland, loc. cit., pi. 44, figs. 3 and 4. f ' Ossemens Fossiles,' 4to, torn. v. pt. ii, p. 347. 



% I'akeontographical Society, vol. for 1851, < Reptilia of the Chalk,' Tab. XXXIII; and vol. for 1854, p. 33. 

 § 'Ossemens Fossiles,' p. 348. || Loc. cit., p. 427, pi. 43, fig. 4. 



