Ch. X.] 



GEOGRAPHICAL RELATIONS OF FOSSILS. 



127 



and had not shed its first teeth. In fig. 112 a front tooth of the 

 same species of kangaroo is represented. 



Fig. no. 



Part of lower jaw of 3facropus atlas. Owen. A young individual of an extinct species. 

 a. Permanent false molar, in the alveolus. 



Fis. 111. 



Lower jaw of largest living species of kangaroo. 

 (Macropus major.) 



The reader will observe that these extinct quadrupeds Fig. 112. 

 of Australia belong to the marsupial family, or, in other 

 words, that they are referable to the same peculiar type 

 of organization which now distinguishes the Australian 

 mammalia from those of other parts of the globe. This 

 fact is one of many pointing to a general law deducible 

 from the fossil vertebrate and invertebrate animals of 

 times immediately antecedent to our own, namely, that 

 the present geographical distribution of organic forms 

 dates bach to a period anterior to the origin of existing 

 species; in other words, the limitation of particular 

 genera or families of quadrupeds, mollusca, &c, to cer- 

 tain existing provinces of land and sea, began before the 

 larger part of the species now contemporary with man 

 had been introduced into the earth. 



Professor Owen, in his excellent " History of British Fossil Mam- 



