152 THE ARCTOG^EIC REALM. [CHAP. 



characterised by the presence of large chambers in the sides of the 

 vertebrae of the neck and trunk, we find not only that several 

 genera, such as Morosaurus, are common to the upper Jurassic 

 and lower Cretaceous strata of Europe and the United States ; but 

 we also find, one genus (Titanosaurus) in India, Europe, and 

 Patagonia, while a second (Bothriospondylus) occurs in countries 

 as far apart as England and Madagascar 1 . Again, in the carni- 

 vorous or Theropodous section of the order, as typified by the 

 English Megalosaurns, we find certain closely allied or identical 

 generic types common to Europe and South Africa. Further 

 evidence in the same direction is afforded by the discovery in the 

 Jurassic of Madagascar of a genus of extinct crocodiles (Steneo- 

 saurus) which were abundantly represented during the same epoch 

 in Europe. Among the class of fishes we have also the genus 

 Ceratodus, now living in Queensland, represented in the Secondary 

 rocks of Europe, India, Africa, and North America. 



With regard to the land-fauna of Australia at the same epoch 

 we have less evidence ; anomodonts, and, we believe, dinosaurs, 

 being unknown from that country. Among the amphibians, how- 

 ever, we find in the extinct order of Labyrinthodontia certain 

 genera, such as Bothriceps and Micropholis, common to Australia 

 and South Africa, both of these being closely allied to the Indian 

 Brachyops. 



This reptilian evidence thus clearly points to the conclusion 

 that during the greater part of the Secondary period not only 

 had Arctogaea a single widely-spread fauna, but that the same 

 fauna was represented in South America, and at least partially in 

 Australia. Hence at this date no zoological realms can be distin- 

 guished, and it was probably not till late in Cretaceous times that 

 Arctogaea was differentiated from the rest of the world as a realm. 

 Needless to say, the great continents and islands during the 

 epochs in question must have had free communication with one 

 another, and it is highly probable, as Dr Blanford 2 suggests, that 

 Madagascar then formed a line of connection between Africa and 

 India. It is possible that even at the early part of the Secondary era, 



1 Possibly future discoveries may show differences worthy of generic distinc- 

 tion between these forms, but this would not affect the general question. 



2 Appendix, No. 8, pp. 88, et seq. 



