1909] JOHNSON — LOCAL ECOLOGICAL STUDIES 7 
tions, do not extend into the contiguous districts. .... These great districts are 
divided into a number of provinces of unequal size, which are limited by changes in 
climate and therefore sometimes distinctly, sometimes vaguely, defined. The 
Atlantic district may be divided into — a northern province, including Maine, Eastern 
Canada, Nova Scotia, Newfoundland, ete.; a middle province limited westwardly 
by the Appalachian chain and extending to southern Virginia; a southern province, 
including the States south of Virginia and Kentucky, and a subtropical province in- 
cluding the point of the peninsula of Florida. 
In 1863 Prof. A. E. Verrill (Proc. Boston Soc. Nat. Hist., X, 260) made the 
dividing line between the Alleghenian and Canadian “coincident with a line which 
shall indicate a mean temperature of 50° Fahrenheit during the months of April, 
May, and June.”’ In describing its course 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 Mts. through the vicinity of Conway, N. H. 
It then bends northward again up the Connecticut valley as far as Craftsbury, Vt.” 
In 1871 Prof. J. A. Allen (Bull. Mus. Comp. Zool., I1) in describing the northern 
boundary of the Alleghenian fauna says: —The line follows the northern boundaries 
of the low lands 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 Mts.” Both Verrill and Allen based their conclusions 
upon the study of birds during breeding season. 
The next paper to consider is that exceedingly interesting chapter by Mr. Scudder 
on the distribution of insects in New Hampshire (in Hitchcock’s Final Rept. on the 
Geol. of N. H., vol. I, chap. xii, 1874). Although only two groups are considered 
— the butterflies and grasshoppers — two which are perhaps the best to start with, 
he points out very clearly the many conditions governing their distribution, as fol- 
lows:— “‘Since insects are not regularly migratory animals; as several generations 
frequently succeed each other during a single season; and, as the winter is passed 
in very various conditions, we can hardly expect their distribution to follow exactly 
that of birds. Various causes may modify unequally the distribution of insects 
belonging to a certain group: too intense cold in our arctic winters; the lack of snow 
during a less severe season; too excessive or too long a drouth in midsummer; or 
too sudden changes of temperature at critical periods. ‘Taking our butterflies only, 
they may be found at every season of the year, even in midwinter, of one species 
or another, in every stage of existence, from the egg through all the larval periods 
and the chrysalis to the imago. The distribution of butterflies is therefore much 
more complicated than that of birds, whose early stages are always passed in com- 
