10 BIRDS OF OHIO. 
Oberlin and in the several regions of the state visited since 
the preparation of this catalogue began, two years ago. In ac- 
cepting records for the state and also for the different coun- 
ties the following rule has been adopted: In order to have 
a place on the state list a specimen of the species must have 
been captured and preserved for some time where it could 
be critically examined. In order to have a place on a coun- 
ty list a species which is rare or casual or accidental in that 
county must have had a specimen captured and critically ex- 
amined, or, if a conspicuously marked species, must have 
been seen under the most favorable conditions by one famil- 
iar with that species. This rule has necessarily resulted in 
the elimination of some species from some of the lists hand- 
ed me, and has relegated to the state Hypothetical List some 
species reported on insufficient evidence as occurring in the 
state. I submit, however, that it is a fair rule, one which 
will safeguard our work. It is far easier to add a species 
to such a list than it is to eliminate it after it is wrongly 
placed there. 
TOPOGRAPHY. 
“The state of Ohio is situated between 38° 25’ and 42° 
north latitude and 80° 30’ and 84° 50’ west longitude. 
Jee It is thus the most southern of the northern tier of 
states, its northern border corresponding in latitude with 
the southern border of Michigan and New York. Its ex- 
treme length is, from east to west, about 220 miles, its great- 
est width from north to south about 210 miles. Its area is 
approximately 40,000 square miles (41,060: land, 40,760; 
water, 300.) (Wheaton.) About three-fourths of the 
state is under cultivation, and of the remaining fourth 
nearly allis woodland. “Before cultivation a few small prai- 
ries in the western and central portions of the state inter- 
rupted the general woodland.” The disappearance of the 
forests has resulted in the almost total extermination of a 
few birds, a marked decrease in the numbers of a large num- 
ber, and an influx of a few species which live in the open 
fields. 
