.. 11.] THE ELEMENTARY FACTS OF DISTRIBUTION. 



25 



named Urotrichus, of which one species inhabits Japan and the 

 other British Columbia. The cuckoo-like honey-guides, forming 

 the genus Indicator, are tolerably abundant in tropical Africa, 

 but there are two outlying species, one in the Eastern Hima- 

 laya mountains, the other in Borneo, both very rare, and 

 quite recently an allied species has been found in the Malay 

 peninsula. The beautiful blue and green thrush-tits forming 

 the genus Cochoa, have two species in the Eastern Himalayas, 

 while the third is confined to Java ; the curious genus Eupetes, 

 supposed to be allied to the dippers, has two species in Sumatra, 

 and the other species two thousand miles distant in New Guinea ; 

 lastly, the lovely ground-thrushes of the genus Pitta, range 

 from Hindostan to Australia, while a single species, far removed 

 from all its near allies, inhabits West Africa. 



Peculiarities of Generic and Family Distrihution. — The examples 

 now given sufficiently illustrate the mode in which the several 

 species of a genus are distributed. We have next to consider 

 genera as the component parts of families, and families of orders, 

 from the same point of view. 



All the phenomena presented by the species of a genus are 

 reproduced by the genera of a family, and often in a more 

 marked degree. Owing, however, to the extreme restriction of 

 genera by modern naturalists, there are not many among the 

 higher amimals that have a world-wide distribution. Among 

 the mammalia there is no such thing as a truly cosmopolitan 

 genus. This is owing to the absence of all the higher orders 

 except the mice from Australia, while the genus Mus, which 

 occurs there, is represented by a distinct group, Hesperomys, in 

 America. If, however, we consider the Australian dingo as a 

 native animal we might class the genus Canis as cosmopolite, 

 but the wild dogs of South America are now formed into 

 separate genera by some naturalists. Many genera, however, 

 range over three or more continents, as Felis (the cat genus) 

 absent only from Australia ; Ursus (the bear genus) absent from 

 Australia and tropical Africa; Cervus (the deer genus) with 

 nearly the same range ; and Sciurus (the squirrel genus) found 

 in all the continents but Australia. Among birds Turdus, the 

 thrush, and Hirundo, the swallow genus, are the only perching 



