OF TILGATE FOREST. 
267 
which the alveoli are formed. The new teeth rise 
in the angle between each triangular plate. None 
of the recent saurians have an analogous structure : 
in the monitors there is no inner alveolar ridge ; 
the new teeth are formed in the substance of the 
gums between the bases of the old teeth : and they 
have no alveoli. The iguanas, which have the 
outer ])arapet very high, extending half-way up the 
teeth, are also destitute of any internal osseous 
border. Hence it may be inferred, tliat this mon- 
ster of the ancient world belongs to an extinct 
genus of saurians, which partook of the characters 
of the crocodile and monitor ; but was most nearly 
related to the latter. * From the straitness of the 
portion of the jaw found by Dr. Buckland, which 
is eleven inches long, it is evident that the jaws 
must have terminated in a flat, strait, and very 
narrow snout. 
T^ertebrcp . — These differ from the vertebrae of 
any known recent monitors, but bear a great re- 
semblance to those of the fossil crocodiles of Til- 
gate Forest, Havre, Caen, &c. They are generally 
a third longer than wide ; slightly concave at both 
extremities ; and more or less contracted in the 
middle ; their annular part is united to the body 
by a suture, as in the crocodile and monitor ; but 
there is a considerable lateral depression immedi- 
ately beneath the annular part. It must, however, 
be confessed, that our knowledge of the osteolo- 
gical structure of the megalosaurus is at present 
too limited to enable us to determine the distin- 
o’liishiiiir characters of its vertebral column. 
O o 
* Tlic teeth are hollow in the young state, but become solid by ago 
