CHAP. xv.J THE NEARCT1C REGION. 137 



together with many northern birds common to both conti- 

 nents. Yet a few Palsearctic forms, not known in other parts 

 of the sub-region, appear here. These are Budytes flava, Phyl- 

 loscopus kennicottii, and Pyrrhula, coccinea, all belonging to 

 genera not occurring elsewhere in North America. Considering 

 the proximity of the district to North-east Asia, and the high 

 probability that there was an actual land connection at, and 

 south of, Behring's Straits, in late Tertiary times, it is somewhat 

 remarkable that the admixture of Palsearctic and Nearctic groups 

 is not greater than it is. The Palsearctic element, however, forms 

 so small a portion of the whole fauna, that it may be satisfactorily 

 accounted for by the establishment of immigrants since the 

 Glacial period. The great interest felt by ornithologists in the 

 discovery of the three genera above-named, with a wren allied to 

 a European species, is an indication that the faunas even of the 

 northern parts of the Nearctic and Palsearctic regions are, as 

 regards birds, radically distinct. It may be mentioned that the 

 birds of the Aleutian Isles are also, so far as known, almost 

 wholly Nearctic. The number of land-birds known from Alaska 

 is 77 ; and from the Aleutian Isles 16 species, all of which, 

 except one, are North American. 



Reptiles. These are comparatively few and unimportant. 

 There are however five snakes and three tortoises which are 

 limited to Canada proper; while further north there are only 

 Amphibia, represented by frogs and toads, and a salamander of 

 the genus Plethodon. 



Fishes. Most of the groups of fresh-water fish of the Nearctic 

 region are represented here, especially those of the perch, 

 salmon, and pike families ; but there seem to be few or no peculiar 

 genera. 



Insects. These are far less numerous than in the more 

 temperate districts, but are still tolerably abundant. In Canada 

 there are 53 species of butterflies, viz., Papilionidse, 4 ; Pieridse, 

 2 ; Nymphalidse, 21 ; Satyridse, 3 ; Lycsenidse 16; and Hesperidse 

 7. Most of these are, no doubt, found chiefly in the southern 

 parts of Canada. That Coleoptera are pretty numerous is 

 shown, by more than 800 species having been collected on the 



