1905] TRANSEAUBOGS OF THE HURON RIVER VALLEY 357 



of the " raised bog." Certain temperature phenomena associated 

 with the bog habitat will be discussed in connection with the analysis 

 of the life conditions obtaining in bogs. 



Rainfall. In the following table is given the mean monthly and 

 annual precipitation for seven stations located within or near the 

 Huron basin. As their individual variation is but small, it is probable 

 that the average for the stations gives a fair estimate of the rainfall 

 and its distribution. Appended are the corresponding records for 

 the maritime region of eastern Canada : 



MEAN PRECIPITATION IN INCHES. 



It will be noticed from the above data that the precipitation is 

 quite evenly distributed throughout the year. It reaches its maximum 

 during the months of May and June, when the vegetative processes 

 of the bog plants are most active. It approaches its summer mini- 

 mum during July . and August, when the temperature commonly 

 attains its greatest height. The former implies that the water level 

 in the bogs is kept at or above the surface of the substratum for weeks 

 at a time. The latter involves strong transpiration on the part of the 

 vegetation, when the water supply must be drawn for the most part 

 from the substratum. The average number of rainy days during the 

 past five years is one hundred per annum. 



The average snowfall in this region during the five years, 1898 to 

 1902, amounts to 38.4 inches (975 mm ). In the case of the bogs this 

 thickness is usually increased by the drifting of snow from the sur- 

 rounding hills. Observations during the past two winters show that 

 the bogs are covered by ice to a thickness of a foot (30 cm ) or more. 



