440 



REPORT OF STATE GEOLOGIST. 



th&m, the internal organs and large masses of flesh are removed 

 and the bones are cleaned in the same way as skulls. Small skele- 

 tons are extremely difficult to prepare and those the size of a dog or 

 fox are better for study. 



CLASSIFICATION. 



The old idea of a species as a group of animals separated from 

 all other groups by characters which are constant and unchanging, 

 has given way to the idea that species are constantly changing and 

 often intergrade. When large collections are brought together from 

 adjoining regions it is often found that the average color, size or 

 other characters of specimens from one locality differ from the 

 average of specimens from another locality, although there may be 

 individuals from either place that bridge the difference. These 

 average characters are now generally considered to be of consid- 

 erable significance and when a number of them are fairly constant 

 for any circumscribed region, they are recognized as being suffi- 

 cient to distinguish species or subspecies. 



It follows, therefore, that individual specimens cannot always 

 be assigned with any certainty to one species or another. However, 

 the purpose of systematic zoology is not to put every animal into 

 a pigeon-hole, properly labeled with a latin name, but to study vari- 

 ations, their causes and their significance to the biological proc- 

 esses. Yet it does not follow that the study of species has no value. 

 If the amateur is unable to determine certainly to which subspecies 

 an animal belongs, he should not be discouraged or feel that the 

 specimen has no value. Its chief value to him will not be in the 

 name which belongs to it as a stuffed skin, l)ut in the relation which 

 it bore to its environment as a living animal. 



It is hoped that the following keys will enable anyone with a 

 little knowledge of biology to identify any mammal found in Indi- 

 ana with a reasonable degree of accuracy when the skin and skull 

 are before him. The larger museums are usually willing to identify 

 and return to the owner any specimens which are submitted to 

 them, especially if duplicates to be kept by the museum are in- 

 cluded. The keys are intended to apply only to species that have 

 been recorded from this State or that i\n' likely to be found within 

 its borders. Some of Ific points in the key and the definitions of 

 the groups will not hold true for mammals in general. 



The arrangement of th(^ k(^y does not follow any natural order 

 of classification arid has been ])lanned solely for the ])ui'|)()se of 



