242 UPPER, OR FLINTY CHALK. 



surface is marked with numerous annular ridges ; a small portion of the 

 spinous process still remains. 



The bone (fig. 5.) is cylindrical in the centre, but the two extremities 

 are nearly flat, and extend in opposite directions. These parts have 

 suffered so much from compression, that it is scarcely possible to ascertain 

 their original shape. It seems probable that they were once convex, and 

 formed articulating surfaces; if this opinion be correct, the bone may, 

 perhaps, have been a humerus. 



Of the nature of the original animal, I must confess myself incapable 

 of offering any satisfactory conjectures : the fangs of the anterior teeth, 

 like those of the crocodile, are hollow, fixed in sockets, and not attached 

 to the jaw ; but their smooth pohshed surface, and flattened form, separate 

 them most decidedly from the animals of that tribe. The posterior teeth 

 are afiixed to the edge of the jaw, a mode of dentature observable in many 

 kinds of fishes. The structure of the vertebra is decidedly that of a fish, 

 the conical cavities being very deep ; and it possesses the annular markings 

 so constantly observable in the vertebrse of fishes. The cylindrical bone 

 is too much injured to allow of any correct inference being drawn from it. 

 From these circumstances it seems probable, that the remains before us 

 are those of an osseous fish, of a species, and perhaps genus, distinct from 

 any previously known. 



Locality. Upper chalk, near Lewes. 

 119. Vertebrae of the fossil Monitor of Maestricht, 

 Tab. xxxiii. fig. IS. Tab. xh. fig. 3. 



The quarries of St. Peter's mountain, near Maestricht, have been long 

 celebrated for the remains of one of the most extraordinary oviparous 

 quadrupeds, liitherto discovered in a fossil state. Several mjignificent 

 specimens of the skeleton of this animal, are figured and described in the 

 splendid work on the fossils of that mountain, by Faujas St. Fond ; and 

 the nature of the original has been ably elucidated by M. le Baron Cuvier, 

 These remains have not previously been noticed in England ; and in- 

 deed, have been found in the immediate vicinity of Maestricht only ; where 

 they occur in a soft, yellowish, calcareous freestone. This Umestone 



