46 6". IV. WILLIS TON 



excellent way, the remains of another lizard from Lesina, closely 

 allied to Aigialosaurus. So evident were the relationships of his 

 Opetiosaunis to Varanus that he was inclined at first to unite 

 them in the same genus. Unfortunately Kornhuber was appa- 

 rently ignorant of the recent publications by Merriam, Osborn, 

 and the writer upon the mosasaurs. Had he been more familiar 

 with the structure of the mosasaurs, I doubt not that he would 

 have recognized more clearly their relationships, and would have 

 detected certain wrong determinations, clearly apparent in his 

 figures, and recognized by Nopcsa — the supraorbital, nasals, 

 columella, etc. There is no supraorbital in the mosasaur skull. 



To Nopcsa,^ very recently, is due the credit for correctly 

 estimating the value of the various annectant characters in these 

 and the other known Cretaceous lizards. His views, though only 

 amplifications and confirmations of those held by other writers, 

 are supported by such undeniably forceful arguments that they 

 cannot be gainsaid. 



Aigialosaiiriis and Opetiosaurus especially, with other Lower 

 Cretaceous lacertilians, were clearly in a direct ancestral line 

 between the mosasaurs and the undoubted direct ancestors of the 

 modern monitors, thus confirming Baur's views and disproving 

 those of Osborn. These semi-aquatic lizards lived, evidently in 

 abundance and in many forms, during the latter part of the 

 Lower Cretaceous time, at least in southern Europe. The earliest 

 mosasaurs of which we have any knowledge are probably 

 those from the Cenomanian of New Zealand, and it is not at all 

 improbable that their birthplace was somewhere near the Medi- 

 terranean Sea, at or near the close of the Lower Cretaceous. 

 Dollo long ago expressed the opinion that the center of disper- 

 sion of the mosasaurs was somewhere in the vicinity of New 

 Zealand, and his views were probably not far wrong. They 

 reached northern Europe shortly after the beginning of the Upper 

 Cretaceous, and North America before the beginning of the 

 Senonian. 



Aigialosaiirus and Opetiosaurus especially — for they are closely 



^ Beiirdge zur Faleontologie und Geologie Oesterreich-Ungarns und des Orients. 

 Vol. XV (1903), Plates V, VI. 



