348 BRITISH FOSSIL REPTILES. 



The articular surface is deeply concave in the vertical direction, indicative of a strong 

 joint and a certain extent of vertical motion, or of retraction and protrusion. Beneath 

 the articular surface is a large rough process or protuberance for the insertion of a 

 powerful flexor tendon. The margin of the articular pulley is slightly raised and 

 roughened, for the attachment of the capsular ligament. The base of the claw-bone is 

 longitudinally striated; the rest of the surface is smooth, and offers the same compact 

 character and colour which are commonly found in the bones of the Megalosauri. On 

 each side of the bone, nearer the lower border, and rather lower down on one side 

 than on the other, is a deep smooth groove, running parallel with the lower concavity 

 of the bone. These grooves indicate the position of the borders of the horny matter 

 of the claw, and also, of the vessels supplying the reproductive matrix of that 

 matter. 



A smaller phalanx of the same type with one side imbedded in a block of 

 Wealden sandstone, fig. 5, shows the whole length, and the sharp-pointed termination 

 of the bone supporting the formidable claw. 



Both the above-described specimens are in the British Museum. 



Mandible and Teeth. Plates 33 and 34. 



The most important evidence of these highly characteristic parts of the Megalo- 

 saurus is the portion of the dentary element of the mandible or lower jaw, from the 

 Stonesfield slate, preserved in the Geological Museum at Oxford, and forming part of 

 the original series of bones described by Dr. Buckland.* This specimen is represented, 

 of the natural size, in PI. 33, fig. 1, from the inner side : a portion of the outer side of 

 the same specimen is given in fig. 2. The entire depth of the ramus of the jaw is not, 

 however, represented by this specimen : a broad and shallow groove along the under 

 and inner surface of the bone indicates where the angular element of the mandible 

 had articulated with this hinder portion of the dentary piece. The portion of the 

 dentary element from a more advanced part of that bone, represented in PL 34, affords 

 a truer idea of the vertical diameter of the mandibular ramus of the Megalosaur. 



The first character which attracts the attention of the anatomist, in the Oxford speci- 

 men (PI. 33, figs. 1 and 2), is the inequality in the height of the outer and inner alveolar 

 walls. This assures him of the saurian affinities of the gigantic reptile ; a similar inequality 

 characterising the jaws of almost all the existing Lizards. But in these the oblique 

 groove, so bounded, to which the bases of the developed teeth are anchylosed, is much 

 more shallow, and is relatively wider; and the teeth, in all their stages of growth, 



* Loc. cit., pi. 40. 



