90 THE BUTTERFLIES OF NEW ENGLAND. 



J. L. LeConte published in the Smithsonian Contributions a colored map 

 of the entomological provinces of North America, in which the eastern 

 district so-called was divided into "1, a northern province, including 

 Maine, eastern Canada, Nova Scotia, Newfoundland, etc., and extending 

 westwardly from Lake Superior to Lake Winnipeg and western Canada, 

 which fades insensibly into the great Arctic district ; 2, a middle province, 

 limited westwardly by the Appalachian chain, and extending to southern 

 Virginia; 3, a western province, including Minnesota and the states of 

 the valley of the Mississippi, as far as the state of that name ; 4, a southern 

 province, including the states south of Virginia and Kentucky ; 5, a sub- 

 tropical province, including the point of the peninsula of Florida ; 6, a 

 subtropical province, including the sea coast of Texas." 



But the principal work that has been done upon the distinction of faunas 

 in the eastern United States has been by the labors of the ornithologists. 

 In 1863, Professor A. E. Verrill pointed out that the dividing line of the 

 Canadian and Alleghanian faunas cut New England in two, and three 

 years later he defined the limits more exactly as "coincident with a line 

 which shall indicate a mean temperature of 50° F., during the months of 

 April, May and June" ; a coincidence which leads him to believe that the 

 distribution of birds is "chiefly influenced, so far as latitude is concerned, 

 by the temperature of the breeding season." Whether, he adds, "a simi- 

 lar law controls the distribution of mammalia, reptiles, insects, etc., can 

 only be determined by further investigation." In describing the course of 

 this isothermal line which marked the northern boundary of the Allegha- 

 nian fauna he says : "It passes south of Moosehead and Umbagog Lakes, 

 but rises somewhat northward along the Androscoggin valley, thence it 

 passes southward of the White Mountains through the vicinity of Conway, 

 N. H. It bends northward again up the Connecticut valley as far as 

 Shaftsbury, Vt., where the mean temperature is 50° 91'." 



This was followed up by the more formal attempt of Mr. J. A. Allen, 

 who followed exactly in the line of Professor Verrill's suggestion that the 

 distribution of the birds in their breeding season should guide the zoologi- 

 cal geographer in his conclusions, and adopted also the indications of the 

 isothermal lines as the basis of his divisions. The line of the division be- 

 tween the Alleghanian and Canadian faunas was described in the following 

 terms : "It ... is an extremely irregular line, with abrupt and deep sinu- 

 osities. Beginning on the coast to the eastward of the Penobscot Bay, it 

 sweeps first somewhat to the northeast, nearly or quite reaching Bangor ; 

 thence passing westward and southward, it follows the northern boundary 

 of the lowlands through southern Maine and southern New Hampshire. 

 In the Connecticut valley it rises farther to the northward, and in its 

 southern descent skirts the eastern base of the Green Mountains, passing 

 to the southward and westward of these highlands in Connecticut, and 



