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gions, — the first a mountain region, corresponding witli tlie Canadian 

 fauna, which includes the whole of the White Mountain district below 

 the limit of forest growth ; and above this a subalpine region, cor- 

 responding generally with the range of the dwarf spruce ; while the 

 extreme summits of Mts. Adams and Jefferson, and a considerable 

 portion of Mt. Washington, including the northern part of the plateau 

 lying south of the highest peak, nearly down to the level of the Lake 

 of the Clouds, belongs to an alpine region, the insects of which 

 show a remarkable correspondence with those of the extreme 

 north of our continent. Peculiar to the alpine region, and not tres- 

 passing at all upon the subalpine, is found a species of CMonoias, a 

 genus peculiar to the very highest latitudes of the continent. Within 

 the subalpine region, and not found outside of it, he discovered a 

 new species of Argynnis (A. montanus Scudd.) belonging to a section 

 of the genus which is peculiar to the subarctic regions, being found 

 neither north nor south of it, and also a new species of grasshopper 

 belonging to the genus Pezotettix (P. glacialis Scudd.), likewise a 

 subarctic genus, though not so strictly limited in its range. As neither 

 of these species of the subalpine region had been discovered to the 

 north, but were represented there by other species of the same 

 genera, he was inclined to think that the facts mihtated against the 

 theoi'ies which had been put forth by others to explain the corre- 

 spondence of the plants of these alpine summits with those of Green- 

 land and Labrador. 



Prof. Wyman inquired whether all the facts might not be ac- 

 counted for on the theory of migration northward after a glacial 

 epoch. 



Mr. Scudder thought they could not, if the species found upon the 

 barren summits of the mountain were, as he believed them to be, dis- 

 tinct from those of the same genus found to the northward. He 

 believed also that we were sufficiently acquainted already with the 

 insects from the north to hazard such a statement ; there was, for 

 instance, a species of Argynnis found from Eastern Labrador to Great 

 Slave Lake, so closely resembling the one found upon the White 

 Mountains as to be readily mistaken for it at first sight, and yet occu- 

 pying the area where, if anywhere to the northward, this White 

 Mountain species would be found ; he believed that we could not ex- 

 pect to find these so closely allied species occupying the same area. 



Prof W. B. Rogers suggested that the facts might be accounted for 

 on the migration theory, if we added thereto the supposition of sub- 

 sequent variation induced by isolation. 



Mr. A. Agassiz remarked that such an explanation would not 

 satisfy us in parallel cases of resemblance, as where, for instance, upon 

 the coast of Washington Territory, at the seashore, we had recalled 



