No. 4.] DR17MM0ND — BOTANICAL NOTES. 223 



occurrence we must revert to some prior age when the conditions 

 of temperature were such as to facilitate their migration from 

 higher latitudes. The fossil remains in the clays and sands over- 

 lying the Erie clays are of a temperate type and preclude the hy- 

 pothesis that the connection took place during their deposition. 

 The Leda clays on the Lower Ottawa, on the other hand, con- 

 tain plants of a northern temperate range, leaving it strongly 

 open to probability that in the higher latitude of the country to 

 the immediate northward of Lake Superior there was during the ■ 

 early periods of the deposits of these clays a temperature cou- 

 irenial to the growth of borcil plants. Nor is this probability 

 dispelled by the hypothesis that the sea shore species were driven 

 inland relatively about tlie same time, as, with the exception of 

 -Cirsiion horridahim, Michx., a perhaps doubtfully maritime 

 plant, and Ramcx marltunas, L., which also occurs in the inte- 

 rior, all of those which are now distributed around the Great 

 Lakes range high on the North Atlantic coast, mingling with 

 semi-Arctic species on the shores of the River and Gulf of St. 

 Lawrence, and on the Nova Scotian coast. 



If the hypothesis which I have here ventured be correct, it is 

 interesting thus to find that the Alpine flora of the White Hills 

 of New England, the boreal colonies of the headlands of Lake. 

 .Superior, the sea-shore plants now spread around the Great Lakes, 

 and the fossil plants of the Leda clays, have all a contempora- 

 neous origin : and that, considering the present normal range of 

 these species on this continent, the wide distribution of some of 

 them over Northern Europe, and the associations suggested by 

 their exceptional locality and habits here, we obain a slight 

 glimpse at the pre-historic record of existing species. 



Intf-a Miuvh -IIikX, 1ST4. 



