12 GENERALITIES. 



CASE or moults several times, after each casting attaining a sudden and 

 rapid increase of size. The larva does not always take the form 

 of a caterpillar or maggot. In some orders (the Aptera, Hemiptera, 

 and Orthoptera) it assumes a good deal of the appearance of the 

 perfect insect. In this imperfect metamorphose it changes its 

 skin as the caterpillars do, and it does not assume a different 

 form for the chrysalis state. 



In .the other orders the larva, on its last change of skin, assumes 

 a new form known as the chrysalis, or pupa, in which state it lies 

 dormant and nearly motionless, shut up like a body in a shroud, 

 until the last change takes place, when it comes out as the perfect 

 insect. This chrysalis, in some cases, merely consists of the 

 hardened skin of the animal itself, and is left unprotected and 

 bare in the open air, or in the earth or other place of conceal- 

 ment, but in other cases a cocoon or case is made by the larva 

 for it previous to and in anticipation of the change — in some 

 spun like the cocoon of the silk-worm, in others composed of 

 fragments of earth or bits of wood, &c., glued together. 



It is to be borne in mind that in Natural History no rule or 

 definition is of absolute and invariable application. Unexpected 

 deviations which puzzle the naturalist and refuse to be bound 

 by his rules, occur in every order. These must be treated as 

 exceptions. 



APTERA (Wing-less Insects). 



The Aptera are arranged in the four following orders, viz. : — 



1. Myriapoda (Centipeds, &c.). 



2. Arachnoids (Spiders, Scorpions, 



and Mites). 



3. Thysanura (Springtails). 



4. Parasitica or Anoplura (Lice). 



Order MYRIAPODS. 



The order of Myriapods is distinguished by the mature animal 



being divided into numerous segments, each bearing two or four 



feet, terminated by a single claw. In the young state they have 



all fewer segments, and at first only three pairs of feet. Some 



