IV.] FAUNISTIC CHARACTERS. 147 



imperfect it may subsequently be found practicable to separate a 

 distinct Mediterranean region. 



In an area of such vast extent as the Arctogseic realm, which 

 embraces countries from the equator to the most 

 northern habitable lands, it is, of course, perfectly the Arctogseic 

 unnecessary to say anything as regards climate 

 and physical features, and we may accordingly proceed forth- 

 with to discuss the leading features of the mammalian fauna as a 

 whole. 



From the Notogaeic realm, in its typical form, Arctogaea is 

 distinguished by the absence of monotremes and diprotodont 

 marsupials, not only at the present epoch, but so far as we know, 

 in past times also. From the Neogaeic realm it is equally well 

 differentiated by the absence at the present day of all the peculiar 

 Neogaeic types of edentates, and likewise at all epochs of Neo- 

 tropical monkeys and marmosets. Such of the former as are 

 found in North America are indeed, as we have seen in the last 

 chapter, only intruders from the south since the epoch of the 

 earlier Pliocene; and in the Miocene the Arctogaeic fauna was 

 further distinguished from that of Neogaea by the absence of the 

 peculiar subordinal groups of ungulates characteristic of the latter. 

 The Insectivora, which with the exception of the solenodons are 

 practically wanting in Neogaea, and are unknown in Notogaea 

 proper, are abundant in all the regions of this realm. 



We might almost go one step further than this, and say that 

 Arctogaea previous to the Pliocene epoch was characterised by 

 being the sole habitat of almost all the families of Eutherian 

 terrestrial mammals, with the exception of those characteristic of 

 the Santa Crucian epoch of Neogaea. But although this would be 

 practically true, it would land us in the difficulty that the Ethio- 

 pian region would probably have to be excluded from Arctogaea, 

 seeing that the higher mammals of the former region are but 

 comparatively recent immigrants. Still, it may be stated that 

 northern Arctogaea is the original habitat of all the modern types 

 of the higher Eutherian mammals. 



Another feature of Arctogaea is the absence at the present day 

 of all marsupials except opossums, while these are only sparingly 

 represented in its western half. Moreover, with the exception of 



102 



