352 The American Naturalist. [April, 
the chart referred to has been severely tested. How did it happen? 
We naturally turn to the climate and its vicissitudes for the explana- 
tion of many things—trivial and grave. Will it help us in the matter 
in hand? 
“ The seasons of 1894 and 1895 were very dry throughout the State. 
Streams and ponds lost all their water and the mud at the bottom was 
dry and parched for months over large areas. Streams of considerable 
volume in ordinary years disappeared entirely for weeks or there re- 
mained only restricted pools here and there. The winter of 1895-6 
was constant for Ohio with less than the average snowfall. The 
weather remained cold until April 10th, when it suddenly became very 
warm and remained so with abundant rain. What resulted as to the 
appearance or non-appearance of dragon-flies? The following notes 
will state some of the observed facts :— 
First—Many species occurred unusually early. The largest number 
recorded in April at Columbus in any previous year was five; this year 
it was ten. They were taken in the following order: Anas junius, 
April 13th; Ischnura verticolis, April 15th; Didymops transversa, 
Basiaeschna janata, Anomolagrion hastatum, Lestes forcipata, Trames 
carolina, Plathemis trimaculata, Libellula semifasciata and Nehalennia 
posita. ‘The variety is not less interesting than the number. Among 
them are some of our largest species and the smallest ; while four fami- 
lies are represented. Five have been taken in Aprilin previous years, 
although not in the same year. Anax, Ischnura, Didymops, Basi- 
aeschna and Tramea have been taken as early in former years, the 
first two much earlier, but the remaining forms not until May was well 
advanced or until midsummer. From this a general statement may 
be made that five of the ten earliest species appeared no earlier than 
usual, but appeared suddenly, i. e., after a very few warm days, while 
five appeared from two to four weeks early than ever before noticed. 
I may extend this record of early occurrence by saying that thirty-five 
species were taken before the end of May, and that several of them 
were those not before seen on the wing until midsummer 
“ In this connection let me say that species common to Ohio and the 
Atlantic coast appear to emerge fully two weeks earlier in the interior 
than on the coast at the same latitude. Nor is it a matter of isotherms 
alone, as a glance at an isothermal map and the recorded captures at 
Philadelphia and New York will show. It is, I suspect, due rather to 
distribution of heat and affects only early appearing species. 
‘Second—It is an interesting question, one often asked, but not 
answered, whether the existing species are fewer than when the country 
