122 Invertebrata. 



their occasional metallic lustre, chrysalides. In this 

 pupa stage the animal lies for a considerable time; 

 this skin then bursts and the perfect insect emerges, 

 at first soft and moist but soon becoming firm and 

 fit for independent life. 



Caterpillars often differ in structure from the 

 adult insect; thus the digestive canal of the cater- 

 pillars of butterflies is fitted for the digestion of 

 solid food, while that of the imago or perfect insect 

 is only fitted for sucking the juices of plants. The 

 antennae likewise of caterpillars are attached to the 

 front eoge of the forehead shield, and outside the arti- 

 culation of the mandible, whereas ihe antennae of the 

 imago or perfect insect are articulated further forward, 

 and on a plane with the joint at the base of the man- 

 dible ; the antennae of the caterpillar may therefore 

 represent the long antennae of the crab and lobster, 

 while those of the perfect insect represent the anten- 

 nules of crustaceans Insects display an amount of 

 intelligence far superior to that of the lower verte- 

 brates; ants, wasps, and bees, the most highly or- 

 ganised as well as the most intelligent of the class, 

 exhibit a wonderful power in the mode of ordering 

 and governing their communities, and the skill shown 

 in the construction of their habitations is scarcely 

 inferior to that of man himself. 



There are at least thirteen orders of insects known 

 to the naturalist, a few of the commoner and more 

 interesting representatives of which are shortly de- 

 scribed in the next two chapters. 



