What Is a Mammal? g 
melanoleucus ; no subspecies of this animal are known, nor is 
there a second living species in the genus Ailuropoda. 
Depending upon their relationships to one another, genera 
are gathered together in subfamilies, and subfamilies into fam- 
ilies. Families in turn are bundled up into suborders, and these 
into orders. The orders of mammals are grouped into the few 
subclasses of the class mammalia, which includes all mammals. 
Depending upon the complexity or simplicity of an order, the 
"sub" divisions, subgenera, subfamilies, or suborders, may be 
in use or may be omitted. Illustrating the major steps of this 
system, our Dogs and Wolves of the genus Canis combine with 
several other genera of dog-like animals to form the family 
Canidae. The Canidae, with the Bear family, the Cat family, and 
others, compose the Order Carnivora (flesh-eaters). In conclu- 
sion, when any single species has to be referred to, its family 
and ordinal relationships are left aside. The Wolf is alluded to 
simply as Canis lupus; that and nothing more is its scientific 
name. 
