14 FOOT-NOTES TO EVOLUTION. 
uniformity of type is accounted for. But what of the 
difference of species? If change of conditions may on 
the islands cause great and permanent changes in a spe- 
cies so as to transform it into a different 
Do species species, may not the same change take 
change with . 
ciate? place elsewhere? May it not happen on 
the mainland as well as on the islands? 
And if on the mainland, what guarantee have we of the 
permanence of species anywhere? May they not be con- 
stantly changing? May not what we consider asa distinct 
species be only the present phase in the changing history 
of the series of forms which constitutes the species ? 
The other phase of the problem which was presented 
to Darwin was that of the succession of fossil and re- 
cent mammalia, especially the edentates 
(ant-eaters, armadillos), etc. in South 
America. We find in the extinct species 
the same peculiarities of structure that 
we see in the forms still living. These peculiarities are 
not shown by animals either recent or fossil in other 
parts of the globe. If each of these species has been 
an independent creation, by what law should the re- 
cent forms duplicate the peculiarities of the extinct 
forms? Is the process of creation in some way influ- 
enced by the peculiarities of forms which have pre- 
ceded these in the same region and not by forms which 
live in other regions? The explanation is not to be 
found in the adjustment of species to their conditions 
of life, for under similar conditions in other regions, as 
in Australia, are found forms wholly 
The species of 
South American 
edentates, 
Do species different. But as edentate has suc- 
change with . 
ete ceeded edentate in South America, so 
marsupial has succeeded marsupial in 
Australia. Is the explanation in both cases to be found 
in the supposition that the recent forms in both of these 
N 
