108 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY 
there referred to as the Alleghanian area, the Upper Austral as the 
Carolinian area. Though these faunal areas are easily recognized, 
a more detailed study in this group of insects shows at least one 
other and exceedingly interesting clement: the presence of an 
isolated and quite distinct maritime district (Howe & Allen, Birds 
of Mass., 11-12, 1901) neither Boreal nor Austral, but both curi- 
ously intermingled (Scuddcr, loc. cit., 89-95). 
Dr. Kennedy, in his review of the author's Manual, has at- 
tempted to state the origin of three of these faunas " though obvi- 
ously of necessity [in a] very broad way," and he evidently did not 
distinguish between the Hudsonian and Canadian, but added the 
Lower Austral in which he included one half of the Austral portion 
of the maritime district mentioned. 
The oldest fauna he calls the Transition, — "possibly a relic 
of the pre-Pliocene times, whose species manage to hang on by liv- 
ing in special habitats that as yet are not seriously invaded by more 
modern faunas." "These genera occupy rough country and rapid 
gravelly streams or boggy land." "They are characteristic of the 
central Appalachian system and among them are many rare and 
odd species." Twenty-five species are included here. He states 
that the Canadian species were "probably the first to appear in 
New England after the retreat of the ice," and that the genera to 
which they belong "are holarctic and probably Eurasian . . . 
perhaps having spread into North America during recent inter- 
glacial epochs." Forty-four of our species are assigned to this 
fauna. 
The Upper Austral fauna is the largest, comprising sixty-eight 
species. This he calls "the great Mississippi Valley fauna of ponds 
and muddy streams, a very modern fauna of close species, which 
is at present overflowing into the warmer parts of New England." 
The Lower Austral, of nineteen species, comprises the "odds and 
ends, the pioneers of a very modern fauna . . . which have slipped 
up the narrow, warm coast from the semitropical gulf strip." 
"This fauna must be increasing at present." 
Geologic and Land Control 
No one doubts that a fundamental relation exists between the 
distribution of life, geologic phenomena, and later physiographic 
changes. To interpret these relations correctly is a problem as 
