34 GEOGRAPHICAL DISTRIBUTION'. 



of South America, Asia, and Africa, and are almost completely 

 absent from the vast northern tracts which spread out towards the 

 polar confines, and tend to bring together the terrestrial areas of the 

 Old and the New World. The order is entirely wanting in Europe, 

 and nearly so in North America, the genus Tatusia, an armadillo, 

 alone penetrating within the boundaries of the last into the State 

 of Texas. In Asia no member of the order is found to the north 

 of the Himalaya Mountains. A remarkable example of discon- 

 tinuous habitation among birds is furnished by the Struthiones, or 

 ostrich-like birds, whose members are distributed throughout con- 

 siderable reaches of tropical and sub-tropical South America, Africa, 

 Asia, and Australia, some of the Australian islands, and New Zea- 

 land, and are entirely wanting in Europe and North America. It 

 is a singular circumstance in connection with the distribution of 

 the birds of this very limited order that two genera, so closely 

 allied as are Rhea and Struthio, should occupy areas so distantly 

 .removed from each other as Africa and South America. The 

 Psittaci, or parrots, inhabitants of both the New and the Old 

 World, may likewise be considered as being preeminently tropical 

 and sub-tropical, for although a few examples are found whose 

 range in the Southern Hemisphere ascends to the fifty-fourth degree, 

 yet the true home of the order is located in the zone embraced be- 

 tween the thirty-fifth parallels north and south of the Equator. 

 Being absent from Europe and the greater portion of the continent 

 of North America, the distribution of the order is necessarily dis- 

 continuous. 



