MIGRATION OF TERRESTRIAL VERTEBRATES 297 



of the Dicynodons, Amalitzky has found them in 

 thejupper Permian of the Dwina, and in such 

 quantities that the Russian palaeontologist has been 

 able to reconstitute the complete skeletons of about 

 a dozen individuals. Their unexpected presence 

 in the Northern Continent can only be explained by 

 an African migration, favoured by a temporary 

 communication across the Mesogea, at the time of 

 the great persistent retreat of the sea, which 

 followed upon the Hercynian wrinklings of the 

 terrestrial crust. 



II. MIGRATIONS OF SECONDARY TIMES. Geo- 

 graphical conditions, very similar to those just 

 described, persisted, with a few modifications, during 

 the greater part of the Secondary era. The ob- 

 stacle raised by the presence of the great area of 

 the Mesogean Sea was still at certain moments 

 surmountable. It would otherwise be impossible 

 to explain the presence in the continents, Austral 

 and Boreal, of certain types of terrestrial Amphi- 

 bians and Reptiles. Thus there have been found 

 in the strata of Tiki and of Maleri in the East 

 Indies a few remains of the great Labyrinthodons 

 (Capitosaurus and Mastodonsaurus) which char- 

 acterize, by their frequency, the Triassic strata of 

 Central Europe. The genus Hyperodapedon, of 

 the order of Rynchocephalous Reptiles, is found 

 both in the Trias of Elgin in Scotland, and in the 

 strata of Maleri in Hindustan. But still more 

 important data are supplied to us by the giant 

 terrestrial Reptiles of the order of Dinosaurians. 

 In this group, with various forms, must be quoted 



