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the local flora also brings to light certain suggestive distributional 

 peculiarities. It is found that while the majority of the species 

 which are known to occur in Eurasia, range far to the north on 

 this continent, the endemic species exhibit decidedly southward 

 tendencies. For example, of the 28 endemic Ranunculaceae 

 native to Connecticut, only 5 — about 18 per cent — have been 

 recorded north of New England or Nova Scotia, while at least 5 

 - — in this case more than 50 per cent — of the 9 extra-continental 

 species have a more or less boreal distribution. Similarly, among 

 the bryophytes 84 per cent of the endemic species are apparently 

 confined to latitudes south of northern New England. 



In themselves statistics like these may be interesting, but it is 

 only as they offer some intimation regarding the history and 

 relationships of the flora that they become of any great value. 

 In common with other glaciated regions the modern era of 

 plant life in Connecticut dates back to the period when the 

 continental glaciers receded toward the pole. In order, however, 

 to clearly apprehend not only the origin of the native flora but 

 also its affinities to that of other regions one must journey back 

 to preglacial times. For an extended period during the lower 

 Tertiary there must have existed greater or less continuity 

 between the continental land masses of the northern hemisphere, 

 and during at least a portion of that time the climate in the 

 present subarctic regions must have been sufficiently mild to 

 permit the circumpolar migration of temperate plants. In this 

 and no other manner can the undeniable similarity of certain 

 components, notably the bryophytes, in the vegetation of Europe 

 and North America be accounted for. But with the advent of 

 the climatic changes which caused or accompanied the develop- 

 ment of the continental ice sheet great transformations in the 

 vegetation were induced. As the glaciers advanced southward 

 the temperate plants, unable to withstand the more rigorous 

 atmospheric conditions, slowly retreated, their places being seized 

 progressively by arctic species which during the warmer period 

 of the early Tertiary had apparently been confined to extreme 

 polar regions. The southward margin of the continental ice 

 sheet in the eastern United States is marked by the terminal 



