Fes., 1912. MAmMALs oF ILLINOIS AND WISCONSIN — Cory. 29 
Order GLIRES. Gnawing Mammals. 
Suborder Simplicidentata. Rats, Porcupines, Squirrels, Beavers, etc. 
Suborder Duplicidentata. Rabbits, Hares, Picas, etc. 
Order FERS. Flesh Eaters. 
Suborder Fissipedia. Cats, Hyenas, Dogs, Bears, Raccoons, Skunks, 
Otters, etc. 
Suborder Pinnipedia. Seals and Walruses. 
Order INSECTIVORA. Insect Eaters. 
Suborder Insectivora Vera. Moles, Shrews, Hedgehogs, etc. 
Suborder Dermoptera. Flying Lemurs. 
Order CHIROPTERA. Bats. 
Suborder Megachiroptera. Frugivorous Bats. 
Suborder Microchiroptera. Insectivorous Bats, etc. 
Order PRIMATES. 
Suborder Lemuroidea. Lemurs, etc. 
Suborder Anthropoidea. Monkeys, Apes, Man. 
Having separated the mammals into subclasses, orders and sub- 
orders, the systematist still further divides them into families, sub- 
families, genera, subgenera, and finally into species and subspecies. 
While the various families are, as.a rule, well marked and may be 
recognized without difficulty, the student will find that this is not 
always the case where species and subspecies are concerned, especially 
among the smaller Mammalia. The positive identification of many 
species often depends almost entirely upon cranial and dental dif- 
ferences, and in the case of subspecies the difficulty is increased, because 
here the cranial characters help us little. The coloration of many 
mammals is easily affected by climate and environment. The change 
in the color of the pelage at different seasons of the year is often more 
or less confusing to the student, as closely allied forms occupying 
different areas, which may be perfectly distinguishable at certain sea- 
sons, may not be so at others; furthermore, specimens from intermediate 
localities may be expected to show inter-gradations, which makes the 
problem still more complex. In this connection it should be borne in 
mind that the line of demarcation between a species and a subspecies 
is a purely arbitrary one and is largely a matter of individual opinion. 
In zodlogical nomenclature subspecies are distinguished by a 
third name; for example, Lepus floridanus mearnsii is a race or sub- 
species of Lepus floridanus. 
