III.] CONNECTION WITH AFRICA. 133 



two outlying genera in Madagascar, and a third in the Fiji 

 and Friendly Islands. But fossil iguanas occur in the French 

 Oligocene, and it may hence be suggested that the group may 

 have reached Neogaea via Madagascar and Africa; while if 

 the connection between Patagonia and Polynesia alluded to above 

 were substantiated, the origin of the Polynesian forms could be 

 accounted for. 



During the middle portion of the Secondary period a very 

 curious resemblance between the fauna of Ethiopia and Neogaea 

 is exhibited by the occurrence in both of certain very peculiar 

 reptiles known as Mesosaurns (Stereosternum), which have been 

 referred to the Sauropterygia. Remains of these reptiles have 

 been obtained at San Paolo in Brazil, and in Griqualand West 

 and other parts of South Africa, but nowhere else ; and, although 

 the type may be of northern origin, this curious distribution 

 apparently points strongly to a connection between Africa and 

 South America as far back as the Secondary epoch. This con- 

 nection, as pointed out by Neumayr 1 , was, however, probably by 

 way of the Atlantic. 



Somewhat similar relationships to those of living reptiles are 

 exhibited by fishes, among which the ffaplochitonidce and 

 Galaxiida have been already mentioned. Very remarkable is the 

 case of the lung-fishes Lepidosirenidce, where there is a very close 

 relationship between the West African Protopterus and Lepidosiren 

 of Brazil and Paraguay ; the Australian Ceratodus being markedly 

 distinct from both. Although the two former are unknown as 

 fossils, teeth of the latter are abundant in the Trias and Jurassic of 

 Europe, India, South Africa, and the United States ; while during 

 the Palaeozoic era extinct families of the subclass (Dipnoi) were 

 abundant in the northern hemisphere. Clearly, then, the group was 

 originally northern in origin; and Ceratodus apparently migrated 

 south both into Africa and Australia. Taking into account the 

 Cretaceous separation of North and South America, and the close 

 alliance between Lepidosiren and Protopterus, it is, however, 

 difficult to see how the latter reached its present habitat except by 

 way of Africa. If this be so, and the connection between South 



1 Vide supra, p. IT 8, note. 



