56 INTRODUCTION TO ZOOLOGY. 



mentioned in the table of resemblances. This is not 

 a good definition, but it will do until we can make a 

 better one. When we say of a thing, "This is an 

 insect," we mean that it possesses all the character- 

 istics mentioned in this table of resemblances. 



Logical Definition. 



A Lepidopter is an insect having scaly wings, sucking 

 mouth parts, complete metamorphosis, whose larva is 

 called a caterpillar, and whose pupa is inactive. This is 

 called a logical definition. Its predicate noun is the 

 name of the class to which the order belongs, and the 

 modifying characteristics are the differences which 

 separate the order Lepidoptera from the other orders 

 of the class Insecta. Now, from your table of differ- 

 ences, make a similar definition of each of the other 

 orders of the same class. 



To the Teacher. 



The purpose of making these tables of resemblances and differ- 

 ences is to train the mind in its power of discrimination, compari- 

 son, generalization, and logical definition. TKe tables should be. 

 made by the pupils.'as far as possible without reference to those in 

 the book, which are inserted merely to show how to make such 

 tables and how to use them. 



Review Topics ou Insects. 



1. Name the seven orders of insects. Give examples 



of each. 



2. What is meant by metamorphosis? 



3. Name four stages in the metamorphosis of insects. 



4. What is molting? 



5. Show the necessity for molting. 



6. Describe a compound eye. 



7. What are ocelli? 



8. What are antennae? 



