104 OEIGIN OF LIFE IN AMEEICA 



of the lower slopes of the mountains, and to it belong the 

 typically American alpine species. They reach their greatest 

 development in the southern portion of the Eockies. 



One of the most remarkable features, which I shall have 

 occasion to draw attention to again in another chapter, is the 

 occurrence in the Eocky Mountains of some species of plants, 

 which reappear in the southern Andes, without being repre- 

 sented either in the Mexican highlands or in the tropical 

 Andes. Among these, Professor Engler * mentions the 

 dwarf gentian (Gentiana prostrata), the mealy primrose 

 (Primula farinosa), the hoary draba (Draba incana) and 

 the alpine foxtail (Alopecurus alpinus). All these are 

 common well-known European species. A few more have 

 since been added by Professor Bray f This small group 

 of species is of peculiar interest, not only because some- 

 what analogous instances of distribution occur among insects, 

 but also because this feature is by no means limited to 

 mountain forms. In another chapter I shall allude to : a 

 number of species inhabiting the arid regions of south- 

 western North America that likewise are quite unknown in the 

 moist tropical and sub -tropical belts of country to the south, 

 yet reappear in the extreme south of South America. Whether 

 all these species possess particular facilities for dispersal 

 over wide areas or whether former conditions of land and 

 water were more suitable than they are at present for dis- 

 persal will be discussed later on (p. 414). 



The fauna of the Eocky Mountains resembles the flora in 

 its composition, except that among the higher animals, at any 

 rate, the species are almost all endemic. Two kinds of animals 

 in particular are associated with the Rocky Mountains in 

 sportsmen's minds, namely, the mountain sheep, or big-horn, 

 and the Eocky Mountain goat. The former used to. be known 

 as Ovis canadensis. But from the systematic mill of the 

 zoologist, as Dr. A. E. Brown J puts it, have been produced 1 

 seven new species and sub-species, all very closely re- 

 lated to one another. As already stated, the Kamchatkan 



* Engler, A., "Entwicklungsgeschichte," II., p. 256. 



t Bray, W. L., " Eolations of North American Flora," p. 713. 



J Brown, A. E., " Zoology of North American Big Game," p. 69. 



