10 BIRDS OF OHIO. 
Oberlin and in the several regions of the state visited since 
the préparation of this catalogue began, two years ago. Inac- 
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. 
De@ee 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 all is 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. 
