202 PALEONTOLOGY 



between then; and the true internal alveolar parapet. There 

 run be no doubt that, in the course of the development of these 

 teeth, corresponding changes take place in the jaw itself, by 

 which new triangular plates and alveolar partitions are formed, 

 as the old ones become absorbed, analogous to those concomi- 

 tant changes in the growth and form of the teeth, alveoli, and 

 jaws, which take place in so striking a degree in the elephant 

 The peculiarity of the Megalosaur, as compared with the 

 crocodiles and lizards which have a like endless succession of 

 teeth, is the deeper position of the successional tooth (fig. 7">. 

 c), in relation to the one («) it is destined to replace, and the 

 great proportion of the tooth which is formed before it is pro- 

 truded. The anterior tooth a in this specimen shows at the 

 inner side of its base the commencing absorption stimulated by 

 the encroaching capsule of the successional tooth c below, the 

 crown of which is completed externally, though not consoli- 

 dated. On one of the fractured margins of this piece of jaw, a 

 part of the basal shell of an absorbed and shed tooth remains, 

 with part of the root of the successional tooth, which has risen 

 into place, but which shows its base full of matrix, the pulp 

 not having been calcified at that period of the tooth's growth. 

 In the proportion of the successional teeth which is formed 

 in the formative cavity in the substance of the jaw, the Mega- 

 losaur offers a closer resemblance to the mammalian class 

 than do any of the recent or extinct crocodilian or lacertian 

 reptiles. But the evidence of uninterrupted and frequent 

 succession of the teeth in the Megalosaur is unequivocal : 

 and this part of the dental economy of the great carnivorous 

 reptile is strictly analogous to that which governs the same 

 system in the existing members of the class. The different 

 forms of the teeth at different stages of protrusion did not fail 

 to attract the attention of the gifted discoverer of the -real 

 predatory saurian, in whose words this notice of its dentition 

 i;ia\ he litlv concluded : — 



