THE MEGALOSAURUS. 
205 
have been an enormous reptile, measuring from forty to 
fifty feet in length, and partaking of the structure of the 
Crocodile and the Monitor. As the femur and tibia 
measure nearly three feet each, the entire hind leg must 
have attained a length of nearly two yards. The bones 
of the thigh and leg are not solid at the centre, as in 
crocodiles and other aquatic quadrupeds, but have large 
medullary cavities, like the bones of terrestrial animals. 
We learn from this circumstance, added to the character 
of the foot, that the Megalosaurus lived chiefly upon the 
land. . . . The form of the teeth shows the Megalosaurus to 
have been in a high degree carnivorous : it probably fed 
on smaller reptiles, such as crocodiles and tortoises, whose 
remains abound in the same strata with its bones. It 
may also have taken to the water in pursuit of Plesiosauri 
and fishes. The most important part 1 of the Megalosaurus 
yet found consists of a fragment of the lower jaw, con¬ 
taining many teeth. The form of this jaw shows that the 
head was terminated by a straight and narrow snout. . . . 
In the structure of these teeth we find a combination of 
mechanical contrivances analogous to those which are 
adopted in the construction of the knife, the sabre, and 
the saw. When first protruded above the gum the apex 
of each tooth presented a double cutting edge of serrated 
enamel. In this stage, its position and line of action were 
nearly vertical, and its form like that of the two-edged 
point of a sabre, cutting equally on each side. As the 
tooth advanced in growth, it became curved backwards in 
the form of a pruning knife, and the edge of serrated 
enamel was continued downwards to the base of the inner 
and cutting side of the tooth. . . . In a tooth thus formed 
for cutting along its concave edge each movement of the jaw 
combined the power of the knife and saw ; whilst the apex, 
in making the first incisions, acted like the two-edged 
point of a sabre. The backward curvature of the full- 
1 This “ most important part” is in a case in an upper gallery of the 
Oxford Museum, while the rest of the specimen is in a separate case 
on the ground floor. 
