148 WATER REPTILES OF THE PAST AND PRESENT 



dolichosaurs we can now understand were a side branch from these 

 semiaquatic aigialosaurs which, speciahzing in another direction, 

 quickly came to grief, perhaps in competition with their more 

 agile and skilful short-necked kin. 



Taking all these facts into consideration it seems best to unite 

 the monitors. doHchosaurs, and aigialosaurs into one group of 

 the Lacertilia, the Platynota, intermediate in place between the 

 true land lizards and the truly aquatic mosasaurs. 



MOSASAURS 



At St. Pietersberg, a small mountain in the vicinity of Maes- 

 tricht, Holland, there are immense subterranean stone quarries, 

 which have been worked for more than a thousand years. The 

 stone quarried from them is a sandy limestone of Upper Cretaceous 

 age containing many w-ell-preserved remains of extinct animals 

 that have long been sought by collectors of fossils. In 1776 Major 

 Drouin — an oflficer of a near-by garrison, one of much mihtary 

 importance in those days — secured from one of these quarries 

 some bones of an extinct reptile, which, though of interest, afforded 

 but little information concerning the structure and affinities of the 

 animal to which they had once belonged. In 1780 a very perfect 

 skull, in excellent preservation, of the same kind of an animal was 

 obtained from the same quarry by Dr. Hofmann, an army surgeon 

 of the same garrison, whose interest in su^h things had been incited 

 by Major Drouin's collections. This spcvi.nen, so renowned in 

 science, has had a remarkable and eventful human historw in 

 part related by St. Faujas de Fond, a French commissary of the 

 "Army of the North," and one of the participants: 



In one of the great galleries or subterranean quarries in which the Cre- 

 taceous stone of St. Pieter's Mount is worked, about five hundred paces from 

 the entrance, and ninety feet below the surface, the quarrymen exposed part 

 of the skull of a large animal in a block of stoncvvhich they were engaged in 

 quarrying. On discovering it ihcy suspended their work and went to inform 

 Dr. Hofmann, surgeon to the forces at Maestricht, who for some years had 

 been collecting the fossils from the quarry, remunerating the workmen liber- 

 ally for the discovery and preservation of them. Dr. Hofmann, arriving at the 

 spot, saw with extreme pleasure the indication of a magnificent si>ecimen; he 

 directed the operations of the men, so that they worked out the block without 



