126 BUTTERFLIES 



south to Virginia and Pennsylvania and west to Nebraska, 

 Montana, and Washington. 



The Mountain Silver-spot 



Argynnis atlantis 



If one were able to take a Silver-spot Fritillary and re- 

 duce its size about one third he would have a wonderfully 

 good imitation of the present species. Except for the size, 

 about the only difference in the markings is found in the 

 blackish border along the margins of the Mountain Silver- 

 spot which is not present in the other species. The buff 

 sub-marginal border line on the under surface of the wings 

 between the rows of silver spots is also wider in the moun- 

 tain species. 



The distribution of tliis butterfly justifies its name. It 

 is preeminently a northern species, being especially abund- 

 ant in the White Moimtains of New Hampshire and rang- 

 ing northward far into Canada and west through British 

 America as far as the Mackenzie River. A pair of these 

 butterflies were captured by Merritt Carey on July 16, 

 1903, on the summit of Mount Tha-on-tha, in the Nahanni 

 Mountains, at an altitude of 2,500 feet. The southern 

 limit of its distribution approximates the isotherm of 

 forty-five degrees. It extends southward in mountainous 

 regions through New York and Pennsylvania and is found 

 in Michigan, Illinois, and Iowa. It also occurs in the 

 Rocky Mountain region of Colorado. 



The various species of Argynnis show a remarkable uni- 

 formity in their life-history. Like the others, this butterfly 

 is single-brooded, laying the eggs on or near violets late in 



