III.] ORIGIN OF SANTA CRUZ FAUNA. I2/ 



Notogaeic and Neogaeic mammals ; and it is easy to imagine that 

 the Polynesian mammals (if they existed) were drowned out by 

 submergence, as has undoubtedly been the case with many of 

 those of the West Indies. In dismissing this part of the subject, 

 it may be observed that it appears impossible to adequately 

 explain the presence of a Notogaeic element in the fauna of 

 Neogaea without the aid of some form of southern land connection; 

 although there is not sufficient evidence to show in what latitude 

 such connection (or connections) existed. 



Attention must now be directed to the Santa Crucian mammals 

 other than marsupials. With the exception of the edentates, which 

 probably originated in Neogsea, or possibly in some still more 

 southern land, all the evidence points to the whole of these 

 being originally of northern derivation ; the ungulates having 

 affinities with the ancestral types from which the earlier Tertiary 

 perissodactyles were descended, while the rodents have certain 

 relationships with the early European members of the order. The 

 monkeys again were probably descended from lemuroids ; and 

 the solenodons are evidently related to the Old World insectivores. 

 It has been shown that this portion of the fauna did not come 

 from North America; and it is certainly not derived from Notogaea. 

 Accordingly, the only route by which it could have entered is by 

 way of Africa. The only marked community between the Ethio- 

 pian and Neogaeic faunas as regards mammals relates to the hystri- 

 comorphous rodents ; but this community is a very marked one, 

 and difficult to explain on any other hypothesis than that of a 

 connection between the two areas. The possibility of a close 

 community of origin between the toxodonts and the hyraces has 

 already been mentioned ; and if it be substantiated, it will be 

 highly important. Of course, on the supposition of an African 

 origin for the eutherian mammalian fauna of Tertiary Neogaea, 

 it must be taken for granted that the ancestral types entered 

 Africa long before the progenitors of its modern fauna ; 

 although probably not before the ancestors of the Malagasy 

 fauna. It may be objected that we ought to find Neogaeic 

 Tertiary types of ungulates in Africa ; but we are unacquainted 

 with the Tertiary palaeontology of that country, and it is 

 quite probable that the peculiar subordinal Neogaeic types of 



