Ward—The Variations in Proportions in Bats. 631 
to make a study of individual variation was furnished by an 
accident that confined me to my room for several weeks. The 
variations noticed were mostly such as could best be recorded in 
measurements. 
The specimens measured were all preserved in alcohol, used as 
weak as possible, and were mostly examined within a compara¬ 
tively short time after collection. The measurements, excepting 
length of head, were taken with a needle-point compass and ap¬ 
plied to a diagonal scale giving tenths of a millimeter; but in 
the record fractions were disregarded and the nearest whole 
number used. The length of head was measured between the 
parallel jaws of a caliper registering millimeters. Every meas¬ 
urement was taken at least twice to guard against possible error 
and all were taken in as nearly as possible the same manner. 
The length of body and the measurements of the ear would 
naturally be the most liable to variation and probably would 
not be repeated by another person with exact correspondence ; 
but the measurements of the metacarpals and phalanges of the 
wings allow of no increase or diminution due to degrees of 
extension and so may be considered wholly reliable, subject only 
to the error of personal equation. Where peculiarities, such as 
marked differences in proportion, were noted, the specimens 
were again subjected to examination for possible error. All 
specimens showing malformations due to injury were excluded 
so that the series may be relied upon as normal. A large num¬ 
ber of the specimens were captured by hand thereby avoiding 
broken bones. Where specimens were shot and bones were 
broken measurements of these broken members were not taken 
and the blanks in the lists are accounted for by this or other 
accidents rendering such measurements unreliable. The list 
numbers used are those with which the specimens are recorded 
in the museum in Tacubaya of the Obmision Geografico Explora- 
dora de Mexico; and my thanks are due to Prof. F. Ferrari- 
Perez, chief of the Natural History Section of this commission 
for allowing me to use these specimens as well as for many 
other favors. 
As a study in individual variation in this group of mammals, 
the making of the lists seemed worth my while and as some 
species were represented by a larger number of specimens than 
are usually at the disposition of naturalists for examination, the 
publication of the tables may be of interest. 
