1913 ENTOMOLOGICAL SOCIETY. 33 



Canada, including, according to our map, practically the whole of the prairie 

 country as well as the semi-arid district in the southern part of the interior of 

 British Columbia. Part of the humid region on the Pacific Slope is also included 

 in this zone, though the fauna and flora of this region are extremely different from 

 rhat of the prairies. 



To the present writer it seems that the northern boundary of this zone is 

 placed too far north in the Prairie Provinces as compared wi.th the corresponding 

 boundary in Ontario. This seems to be true at least in regard to the Odonata and 

 Orthoptera, as I have received from within the limits of the Transition Zone in 

 Manitoba and Saskatchewan some very decidedly boreal species which do not 

 appear to occur in Ontario south of the 'Canadian Zone. It may be noted in this 

 connection that the mean July isotherm of 65 deg. P. corresponds fairly closely to 

 the southern boundary of the Boreal Region in the Eastern Provinces, but does not 

 run so far north in Manitoba and Saskatchewan. 



In the arid district of the Transition Zone, there are certainly many species 

 of both plants and animals which are common to the Transition Zone of the East, 

 but these are mostly boreal species of transcontinental distribution, and there is 

 but little in the austral element of the two regions to warrant their inclusion in 

 the same zone. The physical conditions of the western prairies and eastern forests 

 are, however, so unlike that it is somewhat difficult to compare them. In the Or- 

 thoptera, most of the austral species are of south-western origin, the Carolinian 

 element being decidedly lacking. 



Before closing this brief survey of the faunal zones of Canada, we 

 must not fail to make mention of the conditions met with in British 

 Columbia. The composition of its fauna, however, is too little known to 

 warrant any positive statements concerning it. Though most of it is included in 

 Merriam's Boreal Region and in the great transcontinental, forest belt, most of 

 the trees belong to different species from those of the eastern part of this region, 

 and similar statements could probably be made of any group of plants or animals 

 inhabiting it. The fauna and flora of this region seem to have entered it primarily 

 from two directions, viz., from the south-west and from Asia. The bulk of the 

 species seem to have entered from the Rocky Mountains and Pacific Coast south of 

 the Canadian border, and many of these have decided Californian and Mexican 

 affinities. On the other hand, there are many species of distinctly Asiatic type, 

 which do not occur on the eastern side of the continent. The presence of such 

 forms, particularly in the Alaskan region, is important evidence of the existence of 

 a land-bridge across Bering Sea in early glacial times. To a limited extent this 

 western region has also been invaded by north-eastern forms. 



Finally, let me call your attention to the close relationship that exists between, 

 the boundaries of the faunal zones of our map, as far as Canada is concerned, and 

 the mean isothermal lines for July. According to Merriam, the southward distri- 

 bution of northern species is determined by the mean temperature of the hottest 

 time of the year, which should not be very different from the mean temperature 

 of July. Thus the present map is essentially a map of temperature zones, but not 

 one of primary zoogeographical provinces. 



In conclusion, I should like to impress upon all collectors the value of keep- 

 ing in mind the standpoint of geographical distribution, while on their collecting 

 trips. Not only will the data for a proper understanding of the problems of zoo- 

 geography be more thoroughly accumulated, but the collector will experience new 

 delights in the course of his wanderings, and will feel more keenly than ever the 

 rare pleasure of collecting in a new locality. 

 3 E.S. 



