170 BRITISH FOSSIL REPTILES. 



the matrix ; the margin of this circular aperture is slightly raised. These plates 

 show, or have been resolved into, three lamellag, each less than a millim. in 

 thickness ; part of one lamella, and an impression of another, is shown on the 

 slab containing the teeth and bones ; parts of three lamellfB of one of the plates 

 adhere to the counterpart block. The matrix near what seems to be the pupillary 

 border is stained of a darker colour than the rest, I deem it probable that we 

 have here an indication of the eye-ball of the Megalosaur, and that the pupillary 

 corneal part of the ball was strengthened by a few large sclerotic plates. The 

 indicated diameter of such eye-ball is two inches. The attention devoted to this 

 part of the fossil was requisite to determine whether it might be part of a lacrymal 

 bone or of the sclerotic. 



The orbit in its great relative size and departure from the usual circular form 

 finds, amongst existing Saurians, the 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 inclosed, with the portion 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 jjulp-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, one third the natural size, is shown in 

 fig. 3. The vertical diameter of the bone is 2^ inches at 2 inches distance from 

 the fore end, and gives 2f inches at the opposite fractured end. The symphysial 

 profile is obtusely rounded or moderately convex, as shown in the left ramus 

 (PI. 87, fig. 2). The foremost tooth rises at half 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 

 fuU 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 



