DISTRIBUTION OF ORGANISMS. 



FIG. 106. 



213 



Ornithorhynchus. 



Keverting to the genealogy of the higher orders of Mam- 

 malia, we find ourselves introduced by the cetiosaur and the 

 remark as to the osteology of the dugong, into the confines of 

 the marine or fish-like order of their class. In this group of 

 animals, what first strikes us is that, while united by a com- 

 mon medium of existence, and some peculiarities fitted thereto, 

 they are otherwise extremely various, as much so indeed as 

 all the land mammalia together. The whale, the dolphin, 

 the seal, are animals fully as different from each other as 

 the panther and the elephant, the deer and monkey. Natu- 

 ralists now begin to say that the Carnivora (lions, bears, 

 genets, shrews) are represented in the seals, and the great 

 pachyderms in the whales ; the ruminants, also, in the herbi- 

 vorous cetes (manatus and dugong). Obscure as is our 

 knowledge of the aquatic mammals, this relation is indubitable, 

 but its real character has never been read. It becomes quite 

 intelligible when we arrive at the idea of a genealogical 

 system ; but in no other way, to all appearance, can it be ex- 

 plained. 



The aquatic mammals are not properly one distinct order, 

 nor two either. They merely form the initiatory stages of 

 certain terrestrial orders, a cross section, as it were, at the 

 bottom of those orders, and part of the composite chain by 

 which they are connected with the reptiles. 



The first of these terrestrial orders is that of the Carnivora : 

 it starts in the seals (Pkocidce). We see in that family genera 

 bearing a positive resemblance to both the ursine and the feline 

 tribes, and respectively called in consequence sea-bears and sea- 



