338 PROF. OWEN ON THE SKULL OP MEGALOSATTRTTS. 



circular form finds, amongst existing Saurians, its nearest approach 

 in the large carnivorous Varanians. The comparatively small 

 size of the eye-ball accords with the hugeness and carnivority of the 

 extinct terrestrial Dinosaur. 



An indication that the lower jaw had been enclosed, with the por- 

 tion of the upper one above described, in the same mass of matrix, 

 is given by the impression of the crown of the mandibular tooth 

 projecting into the interval between the third and fourth maxillary 

 teeth, in the block exposing the upper jaw, the tooth leaving that 

 impression being preserved in the counterpart block. The extent 

 of the mandibular tooth so preserved measures 1 inch 8 lines, and 

 includes the upper two thirds of the crown : the breadth of the 

 fracture is 8 lines ; and this exposes the termination of the pulp- 

 cavity. 



I infer therefore that the portions of mandible with teeth next 

 to be described are not only Megalosaurian, but formed parts of the 

 same individual as the preceding fossil. They were worked out of 

 separate blocks of freestone which were in contiguity prior to the 

 masonic operations. 



The first portion shows the outer side of the anterior ten inches of 

 the right mandibular ramus, a portion of which, two thirds the natural 

 size, is shown in fig. 3. The vertical diameter of the bone is 2k 

 inches at two inches distance from the fore end, and 2| inches 

 at the opposite fractured end. The symphysial profile is obtusely 

 rounded or moderately convex, as shown in the restoration of the 

 skull (Cut, p. 340). The foremost tooth rises athalf an inch therefrom. 

 This tooth gives an exserted length of crown of 2^ inches, with a 

 basal breadth of 9 lines. An interval of nearly one inch divides it 

 from the second tooth, also fully developed, but with the apical half 

 of the crown broken away. The third, fourth, and fifth mandibular 

 teeth rise at similar intervals ; and only the fifth falls short of full 

 protrusion, the upper two thirds of the crown appearing above the 

 alveolar border. The base of a sixth tooth, with a large formative 

 cavity, is discernible, with the usual interval between it and the 

 fifth. So much of the outer surface of the bone as remains indicates 

 a shallow longitudinal groove, nearly midway between the upper 

 and lower margins, and disappearing beneath the second tooth in 

 place : anterior to this the bone shows a few irregular shallow pits, 

 some of which, occupied by matrix, indicate nervous or vascular 

 foramina. In the same block are two fragments of probably the 

 left ramus of the same jaw, each in connexion with, or lodging, a 

 portion of a fully developed tooth. 



A larger portion (fig. 2), which has been freed from another block, 

 consists of the anterior part of the left mandibular ramus of the 

 same skull, 8 inches in length, but wanting the symphysial end. 

 On its outer side it repeats the longitudinal groove, here extending 

 backward three inches beyond the part interrupted in the right 

 ramus. In advance of this groove there are similar depressions and 

 indications of the small nervo-vascular foramina. As the lower border 

 of the present fragment begins to bend upward at the anterior 



