182 DE. A. s. wooDWAiiD ON EXTINCT [Mar. 5, 



.similar teetb during the Cretaceous period in tlie Northern liemi- 

 spliere ; but it seems probable that the completion of the tooth- 

 sockets and the paucity of successional teeth in Genyodectes are 

 characters indicating that it was one of the latest and most 

 specialized members of its race. 



IV. Conclusion. 



The extinct reptiles discovered in the red sandstones of Northern 

 Patagonia are now of special interest from two points of view. 

 Firstly, there is a curious mixture of types which in other parts 

 of the world belong to more than one geological period ; secondly, 

 the occurrence of Miolania seems to confirm the much-discussed 

 theory of an old Antarctic continent and a former connection 

 between South America and Australia. 



The association of ancient with modern types of reptiles is 

 especially remarkable. The nearest allies of the Crocodile Noto- 

 suchus occur in the Upper Jurassic of Europe, while the latest 

 known Dinosaurs are undoubtedly Upper Cretaceous both in Europe 

 and North America. Miolania, on the other hand, occurs in the 

 latest Pleistocene deposits of Queensland, associated with extinct 

 though typically Australian mammals ; while the smaller species 

 of the same genus found in Lord Howe's Island must be regarded 

 as equally modern. Dlnilysia, again, is a typical South American 

 Snake, such as might have occupied an appropriate place in the 

 fauna of that continent u hen the gigantic GJyptodonts and Ground- 

 Sloths were flourishing. The anomaly may be explained either 

 (i.) by supposing that the essentially Mesozoic land-reptiles survived 

 to a later period in Patagonia than elsewhere ; or (ii.) by assuming 

 that geologists are mistaken concerning the age and apparent 

 contemporaneity of some of the red sandstones of Neuquen and 

 Chnbut. The problem must be solved by future geological 

 research. 



Of all the similarities between the South- American and Austrahan 

 faunas, perhaps none is more striking than the essential identity 

 of the extinct Miolania in the two regions. There can be no doubt 

 that this was a truly terrestrial or marsh Chelonian; while it seems 

 at first highly improbable that so remarkably speciahzed a dermal 

 armour as it possessed could be independently acquired by distinct 

 animals in two different regions of the globe. The theory of a 

 former land- connection between South America and Australia 

 seems therefore to receive important support from the nev/ 

 discovery now described. It must, however, be remembered that 

 during the late Mesozoic and early Cainozoic (Tertiary) periods, 

 the PleurodiranChelonia had a much wider distribution than at 

 present — were, in fact, perhaps nearly a3 cosmopolitan as are the 

 Cryptodira in the existing world. It is known that the doubly- 

 armoured Herring Dijjlomystus, now living in the rivers of Chile 

 and New South Wales, was a widely distributed marine fish in the 



