THKIR DISTRIBUTION IN NEW ENGLAND. 975 



The American species flies in July aiul :it tlic ciul df August. Tlic Init- 

 terflies are rather local and their flight low and not very active. The eggs 

 are wliite, ecliinoid shaped, strongly pitted and with prominent, rounded 

 elevations. The caterpillars, which are imperfectly known, feed upon 

 Polygonaceae and especially Runicx. Tlic clirysalis has nuu'li the form 

 of that of Heodes and of a similar d\dl brown. 



EXCURSUS XXXVI.— THE DISTRIBUTION OF BUTTERFLIES 



IN NEW ENGLAND. 



The wooils, the rivers, iind the niedovvcs greene, 

 "With his aii-c-<'iitting wings he measured wide, 

 Xe dill he leave the inountaines bare iinseene, 

 Nor the raiilce grassie fenues delights iintride. 



Spenser. — Muiofiutmos. 



Probablv no district of equal extent in the United States possesses a 

 greater variety of butterfly life than New England. Extending in a north- 

 easterly direction over more than eleven degrees of latitude and sc* en and 

 one-half degrees of longitude, its broad north-westerly side supporting a 

 range of hills which forms the backbone of the district, higher than any 

 equivalent range east of the Eocky Mountains, it exposes a vast coastal 

 plain to the open sea, one-half of which receives the warm waters of the 

 Gidf Stream, the other the colder Arctic flow which hugs the shore as far 

 as Cape Cod. Its north-easterly extremity stretches far toward the Gulf 

 of St. Lawrence, with its sub-arctic cold, and nourishes only the butter- 

 flies of the Canadian fauna, while its low, sandy southern shore receives 

 many a wanderer from the Carolinian fauna, which struggles to maintain 

 a foothold and even to penetrate along the coatt and up the wainur river 

 valleys. On tlie summits of the highest mountains we are even brought, 

 as it were, into the very heart of Labrador and Greenland, and from 

 there, one may say with but little exaggeration, we may look upon the 

 tropica. 



The main distinction, then, which we find among the butterflies of dif- 

 ferent parts of New England is that we find within its limits a commingling 

 of northern and southern faunas. Indeed, as we have pointed out in the 

 Introduction to this work, the line between the Allejrhanian and Canadian 

 faunas divides it near the middle in an irregular course, influenced largely 

 by the flow of the streams and the trend of the mountain chains. The 

 different species which find their northern and southern limits within these 

 districts have been detailed in the chapter of the Introduction bearing upon 

 this point, and there are only one or two additional matters which may 

 claim our attention here. 



The distril)ution of butterflies, as is well known, depends very largely 

 upon that of their food plants, and the latter in most regions upon the 



