AN ARRANGEMENT OF THE MAMMALIA. 67 



So, for all these good and sufficient reasons, I am of the 

 opinion that at present, at least, we are hardly prepared to in- 

 clude in a classification of existing mammals, those which we 

 only know hy their fossil remains, — certainly not in all in- 

 stances. For example, we are by no means sure that the ani- 

 mals, by many thought to be Triassic mammals, may not, after 

 all, turn out to be anomodonts, and this is probably true, too, 

 of some of those of the Jurassic, which are known to us only 

 through very fragmentary remains, Therefoie to include in my 

 classification such extinct groups as the Polyprotodontea and 

 the Multituberculata, placing the former near the marsupials and 

 the latter near or with the existing monotremes, would neither 

 avail or mean much; moreover the relationships are by no 

 means proven. 



The horse, deer, camel, rhinoceros, hippopotamus, pig and 

 various other lines represented by a great quantity of fossil 

 material would fit in much better, and in the case of those of 

 the most recent geological horizons, would, in numerous in- 

 stances, simply fall into modern existing families, and so not 

 affect classification at all. As we trace the ancestors of many 

 of these, however, through the more or less abundant material 

 at hand, we find ourselves soon confronted with vastly different 

 forms, the relationships of which to existing mammals are by 

 no means understood and settled; and it would be more than 

 provisional to include them in any scheme of classification of 

 existing Mammalia. 



Of course, much that has been said in the last few para- 

 graphs applies more especially to such schemes of classification 

 that do not stop at the family groups, but include genera or 

 mayhaps species which is not the case with the one here pre- 

 sented. This is all that is necessary to be said upon this point. 



The mammalian taxonomers of some future century may 

 be prepared, perhaps, to combine in a classification the then 

 extinct and existing mammals, or even to draw a fairly correct 



