152 
REPTILES OF THE CHALK. 
the Maestricht animal are associated, M. Cuvier 
concluded that the original was an inhabitant of the 
ocean ; a circumstance very remarkable, since none 
of the existing lacertae are known to live in salt 
water.* 
Crocodile There are three teeth in my cabi- 
net which possess the external characters of those 
of the crocodile, but do not contain within them 
traces of the supplementary tooth. Baron Cuvier, 
to whom I showed them in 1831, decided that 
they must have belonged to some species of this 
genus. 
Undetermined Reptiles. — A lower jaw, with 
twelve smooth, pointed, slightly convex teeth, was 
figured in the Fossils of the South Downs, as the 
jaw of a fish. There can scarcely admit of a doubt 
that it belongs to a saurian animal : a figure is 
annexed. The original is five inches long ; the 
fangs of the anterior teeth, like those of the croco- 
dile, are hollow, fixed in sockets, and not attached 
to the jaw ; but their smooth polished surface, and 
flattened form, separate them most decidedly from 
the animals of that family. The posterior teeth are 
affixed to the edge of the jaw, a mode of dentature 
* Vide Cuvier’s interesting description of the remains of the animal 
of Maestricht, Oss. Foss, tome iv. 
In the course of this volume it will be seen that the Mososaurus had 
an os tympani, approaching more nearly to that of the monitor than 
to the crocodile. As the bones of the extremities have not been dis- 
covered, it is by no means certain that the original was exclusively 
aquatic, much less that it was confined to the ocean. 
Teeth of the Mososaurus have been found in America by Dr. Morton ; 
they so perfectly approximate to tliose of Maestricht, that they must 
have bclongetl to the same species. 
