io CLASSIFICATION OF THE MAMMALIA. [CHAP. i. 



The accompanying diagram (page n) is intended to 

 exhibit the relationships which appear to exist between the 

 different groups of recent Mammalia. If all known extinct 

 forms were inserted, many of the intervals between the 

 boundary lines of the groups would be filled up ; other- 

 wise no great modification would be required in their relative 

 position. But our knowledge of the systematic position 

 and relations of the past forms of Mammalian life is in 

 general so imperfect and fragmentary, that it seemed best 

 to confine the diagram to a representation of the present 

 condition of Mammalian life upon the earth. 



