568 PHYSICAL GEOGRAPHY. 



the Northern states ; and we cannot suppose there would be any differ- 

 ence in the manner of the introduction of the two classes. Once intro- 

 duced, the salt-loving plants would find a congenial habitat, and would 

 not disappear, even after the removal of the estuary. 



There is hardly a possibility that the seeds of these plants could have 

 been preserved in the ground during the long ages of glacial cold, and 

 revivified after the return of warmth. Besides, the glacier, in plowing 

 out the valleys, would have transported these seeds far to the south, and 

 fresh debris from the north would have covered up the briny exudations. 



Botanists have described many maritime plants from the salt regions 

 of the Rocky Mountains. These are the descendants of those which 

 were introduced by oceanic migrations in Cretaceous or Tertiary times ; 

 and, as the glacier never covered them, they have continued uninter- 

 ruptedly till now. 



The distribution of certain forms of animal life confirms our theory. 

 A species of marine crustacean has been found recently by Dr. William 

 Stimpson, by dredging in the waters of Lake Michigan. Girard de- 

 scribes a fish from these northern lakes, Triglopsis Thompsoni, all whose 

 affinities are marine. Add to these the oft-quoted instance of marine 

 insects found on Lake Superior by Dr. Leconte, and a parallel case of 

 the discovery of two species of Mysis in Norwegian lakes. Also, accord- 

 ing to F. W. Putnam, director of the Peabody Museum, in Salem, Mass., 

 the fishes found in Lakes Champlain and Erie are so much alike, though 

 widely separated, that an ancient salt-water connection is needed to 

 explain their present isolation. 



Perhaps other evidences of a marine connection may be found in Lake 

 Winnipiseogee. The fishermen are now familiar with a fresh-water smelt 

 there, which is said to be the same species with the one so abundant in 

 the ocean. This fact is certainly suggestive of a former connection 

 between the lake and ocean. 



THE WHITE MOUNTAIN PLANTS. 



Concerning these I will present a few statements prepared by Dr. Na- 

 than Barrows, of Meriden, at my request, and read before the Dartmouth 

 Scientific Association, September 28, 1870. 



The most interesting part of the botany of New Hampshire is that 



