976 THE BUTTKRFLIES OF NEW ENGLAXl). 



character of the soil. In Xi'w Enghiiul, however, buried as it is from 

 one extroinitx to the otlier l)eneath a vast slieet of drift, this element has 

 the very weakest ])ro[)ortions. The distrihution of limestone areas has in 

 most countries very close connection with the distrihution of plants, and 

 were it not for this covering of drift, which envelops the \\liok' of New 

 iMialand, we niiaht look here for some considerable difference between 

 the eastern and western portions, since the limestones of New England 

 are very largely confined to the Connecticut valley and the region west of 

 it. Their effect, however, upon the actual character of the soil is, com- 

 pared to that which we find in other regions, and consklcring theu' ex- 

 tent, exceedingly small, and, jierhaps consequently, we have scarcely any 

 butterflies whose limitations in an east or Avest direction can in any way 

 be claimed to be dependent upon any other element than that of a 

 northerly or southerly exposure. Polygonia satyrus, indeed, has been 

 found only at a single point just outside the north-western extremity of 

 New England, and here finds its easterly limit. It is a butterfly which 

 belongs, properly speaking, to the other side of the continent, but, like 

 others in the same category, doulitless extends across nearly the entire 

 continent north of our own boundaries. But such examples as this should 

 be looked upon rather as northerly forms which, belonging to the western 

 and centi-al portions, but traversing the continent in northern latitudes, 

 naturallj- invade our territory from the \^■est. The same should be said of 

 Rusticus scudderii, the relations of which to New England are those of a 

 northerly and westerly neighbor. Eurymus eurythemc is a fuither example. 



The only instances known to me where butterflies, entering New Eng- 

 land from the west or west and south, do not cross the district at least 

 nearly to its eastern boundaries are : Chrysophanus thoe, wdiich has never 

 been found farther east than Amherst in the Connecticut Eiver bottom, 

 Thecla acadica, whose New England distribution is exceedingly little 

 known ; and Strymon titus, which appears only to reach the extreme west- 

 ern border of Maine. Of these three, Chrysophanus thoe is the only 

 striking example, and its' limitation may possibly be only apparent, and 

 due to its localization. 



We see, therefore, that the geographical distribution of buttei-flies in 

 New England is almost completely an element of the temperature. The 

 mountains and the streams run in a general north-southerly direction, 

 not only offering no obstacles to the freedom of movement north and 

 south, but affording not infrequently a highway, facilitating movement. 

 The relation of the coastal line to the currents are such that the extrenres 

 of the north and south are intensified. In this narrow area, therefore, are 

 crowded not only abundant representatives of the Canadian and Alle- 

 ghanian faunas, but even some vagrant or ambitious members of the Hud- 

 sonian, upon the mountain tops, and of the Cai'olinian, along the low 

 southern coast. 



