334 



PHYSICAL GEOGRAPHY. 



Mr. Allen's location of the dividing line between the Alleghanian and 

 Canadian faunas, though rather vaguely stated, seems to correspond 

 better with the distribution of butterflies, though it is perhaps still too 

 far north ; and I have colored a narrow band red on Plate B, which will 

 indicate more exactly the limitation which seems to accord best with the 

 facts at my command. This band, striking the Maine boundary opposite 

 the lower extremity of Lake Winnipiseogee, runs in a south-westerly 

 direction nearly parallel with the coast line of Maine, until it reaches th6 

 vicinity of the Monadnock mountain (Hillsborough county), and then 

 turns sharply upward and strikes the Connecticut river at the highlands 

 about Claremont, In the neighborhood of this band (sometimes closely 

 confined to it) are the southern limits of such Canadian butterflies as 

 Minois Alope, and the northern limits of such Alleghanian butterflies as 

 Basilarchia Astyanax, Grapta interrogationis, Vanessa Huntera, Speyeria 

 Idalia, Pterourus Troilus, Erynnis Juuenalis, Anthomaster Leonardus, 

 and Limochores Manataaqua; other species, including northern types like 

 Grapta Faunas and Argynnis Atlantis, and southern types, such as Epav" 

 gyreus Tityrus and Pamphlla Sassacus, find their southern or northern 

 limits, as the case may be, within other portions of the broad blue belt ; 

 while, again, some Alleghanian species, such as Achalarus Lycidas, Pho- 

 lisora Catullus, Amblyscirtes vialis, Ocytes Metea, and Poanes Massasoii, 

 find their northern limit at the southern boundary of this belt ; and some 

 Canadian species, such as Argtis Eurydice and Aglais Milberti, find at 

 this same point their southern limit. 



It is plain that somewhere within this blue belt the dividing line between 

 the Canadian and Alleghanian faunas must be drawn ; and it will proba- 

 bly prove difficult to discover any more exact boundary than this, for we 

 should certainly expect an interdigitation of forms peculiar to the two 

 faunas over some common area; and it is only by direct study of the 

 comparative abundance or rarity of very many species of animals within 

 this broad belt that any more exact limitation can be obtained. The 

 local zoologists of New Hampshire can render science an important ser- 

 vice by a careful record of such facts in as many distinct localities as 

 possible ; only it is essential that such observations be continued through 

 several successive seasons (best, for a decade), for the comparative abun- 

 dance of any one species, in any one locality, depends upon a variable 



