2 5 o THE INTERNATIONAL MONTHLY. 
must be closed ; but it should not be forgotten that it is hardly 
even an outline sketch of a vast subject, for the greater number 
of mammalian order have been passed over in silence. It seemed 
better to concentrate attention upon a few, the history of which 
is fairly well understood ; and these, as Huxley long ago pointed 
out, actually give us demonstrative evidence of the theory of 
evolution. 
