FOSSIL REPTILES. 303 



like those of the monitors. In fact, the Baron observed but 

 one or two specific differences. The first was, that the spinous 

 apophyses of the dorsal vertebrae are much more raised than 

 in the existing monitors, whose skeletons he examined, being 

 almost equal to those of the tail ; the other, that the leg was 

 a little longer in proportion to the thigh and foot. But these 

 differences can in nowise aflfect the just and rigorous determi- 

 nation of the genus. 



We have now to speak of the great and most celebrated 

 fossil Saurian, discovered in the quarries of Maestricht, and 

 which has given rise to many controversies, having been 

 sometimes taken for a crocodile, sometimes for a saurian of 

 some other genus, and even sometimes for one of the cetacea, 

 or of the fish. 



It would appear that its bones have as yet been discovered 

 only in a confined district, in the hills, by which the western 

 side of the valley of the Meuse is bounded, in the environs of 

 Maestricht, and principally in that on which Fort St. Pierre 

 stands, and which forms a sort of cape between the Meuse 

 and the Jaar. 



The formation in which they were found is a soft, crumbly, 

 calcareous stone, many parts of which are easily reduced to 

 powder. Other portions are sufficiently hard for the purposes 

 of building ; and the quarries are now very much extended. 

 Those of Fort St. Pierre are above twenty-five feet in height. 

 The massive limestone above them has been found to be two 

 hundred and eleven feet, and two hundred and thirteen feet 

 has been dug down without any other stone being found. All 

 is of the same character, with the exception of about sixteen 

 feet of vegetable mould, which covers the summit of the hill. 



This massive limestone is then at least four hundred and 

 forty-nine feet in thickness. Lumps of silex have been found 

 in many parts of it. What proves that it belongs to the 

 chalky formation is, that the stone changes by degrees into a 

 true chalk, as one retraces a few leagues the valley of the 



