194 VESTIGES OF THE 



diversity taking place in the lower gradations. No 

 physical or geographical reason appearing for this 

 diversity, we are led to infer that (3) it is the result 

 of minute and inappreciable causes giving the law of 

 oi'ganic de\^elopment a particular direction in the lower 

 subdivisions of the two kingdoms. (4) Development 

 has not gone on to equal results in the various con- 

 tinents, being most advanced in the eastern continent, 

 next in the western, and least in Australia, this inequality 

 being perhaps the result of the comparative antiquity of 

 the various regions, geologically and geographically. 



It must at the same time be admitted that the line 

 of organic development has nowhere required for its 

 advance the whole of the families comprehended in the 

 two kingdoms, seeing that some of these are confined to 

 one continent, and some to another, without a conceiv- 

 able possibility of one having been connected with the 

 other in the way of ancestry. The two great families of 

 quadrumana, cebidse and simiadie, are a noted instance, 

 the one being exclusively American, while the other 

 belongs entirely to the Old World. There are many 

 other cases in which the full circular group can only be 

 completed by taking subdivisions from various con- 

 tinents. This would seem to imply that, while the entire 

 system is so remarkable for its unity, it has nevertheless 

 been produced in lines geographically detached, these 

 lines perhaps consisting of particular typical groups 

 placed in an independent succession, or of two or more 

 of these groups. And for this idea there is, even in the 

 present imperfect state of our knowledge of animated 

 nature, some countenance in ascertained facts, the birds 

 of Australia, for example, being chiefly of the suctorial 

 type, while it may be presumed that the observation as 

 to the predominance of the useful animals in the Old 



