4 
THE STUDY OF INSECTS. 
as red-oak, live-oak, and water-oak. All of the species of oak taken 
together constitute the genus Querctis of botanists. Several species 
of hawks and falcons are classed together by zoologists as the genus 
Falco. 
The genera in turn are grouped into families. Thus the pines, 
the spruces, and the larches resemble each other quite closely, and 
are classed together as the Pine Family (Abietinece) ; the falcons, 
hawks, kites, and eagles are classed together as the Falcon Family 
(Falconidce). 
Closely-allied families are grouped together to form orders . The 
Pine Family, the Cypress Family, and the Yew Family comprise the 
Order Coniferce , or cone-bearing plants, of botanists. The Owl Fam¬ 
ily (< Strigida>). the Falcon Family (Falconidce), and the Vulture Family 
(VuUuridce) constitute the Order Rap lores, or Birds of Prey. 
Closely-allied orders are grouped together to form classes. Thus 
all the orders of birds taken together constitute the Class Aves or 
Birds. 
The classes are grouped into branches , which are the principal 
divisions of the Animal Kingdom.* In studying the different forms 
of animals it is found that there are several distinct types of structure. 
Some animals are built upon one plan or structure, and others on 
other plans. All animals built on the same plan are said to belong to 
the same Branch. Thus the back-boned animals comprise the Bra?ich 
Vertebrata; the clams, oysters, snails, cuttle fish, and certain other 
allied forms comprise the Branch Mollusca ; and the insects, spiders, 
centipedes, lobsters, and their near relatives comprise the Branch 
Arthropoda . 
All the branches of animals taken together constitute the Animal 
Kingdom. 
It is not possible to lay down rules by which these different groups 
of animals can be limited. For, as has been shown in our discussion 
of species, all have been connected in past time by intermediate forms 
But notwithstanding this, each of the terms given above (Branch, 
Class, Order, Family, Genus, and Species) expresses a pretty definite 
conception, which the student will learn to comprehend by practice 
in classifying animals. But the sequence in rank of these groups 
should be learned at the outset. Beginning with the most compre¬ 
hensive it is as follows: 
* The principal divisions of the Vegetable Kingdom are not termed 
Branches ; hence we will not make further use of botanical illustrations in 
this connection. 
