172 MAMMALIAN DESCENT. [LECT. VII. 



Tenrec has as many as eighteen or twenty. If that is 

 not a sort of reptilian character, I do not know what is. 

 This family and others, especially the Lemurs, give 

 the Mascarene fauna a very peculiar, and extremely 

 interesting character ; all the types, as I have said, are 

 marvellously unlike those found on the mainland of 

 Africa, beyond the straits of Mozambique. These things 

 set both the biologist and the geologist speculating as to 

 the changes in the earth's crust that have brought about 

 these remarkable isolations of types, isolations largely 

 due, undoubtedly, to extinction of species. At present the 

 fragmentary state of our knowledge excludes all boasting, 

 so that the biologist is kept in a state of chronic 

 humility. Here, if anywhere, caution is necessary ; we 

 must not imitate the old geographers, who would not 

 suffer any blanks to be left in their maps, and thus 

 came under the lash of the satirist 



"Geographers, in pathless downs, 

 Put elephants instead of towns. " 



Some of the most remarkable and instructive of this 

 variable Order are found just north of the equator and of 

 Wallace's line in the south-eastern part of Asia and the 

 contiguous islands. Of course, south of Wallace's line, 

 in the Australian region, we have Marsupials, and 

 coupled with them, the lowest of the living Birds. But 

 some of the Eutheria living a little further north show 

 that they are not many steps in advance of the low 

 southern types. In Java, and other islands near, as 



