!^6 THE ANIMAL KINGDOM. 



respiration takes place by means of air-bags, the sides of 

 which are so folded as to expose as much surface as 

 possible to the action of the air. This arrangement is 

 something between a water and an air-breathing apparatus, 

 for most of these creatures frequent damp situations. 

 These bags open by spiracles on the under side of the 

 body, and can be closed by horny lips. 



The Spider family secrete a poisonous fluid, which is 

 fatal to insects, and even to small birds. 



Arachnida are divided into three principal groups, viz. : 



MITES, SCORPIONS, AND SPIDERS. 



Mites (Fig. 95) are very small ; in fact, some of them 

 are microscopic members of the group. Some live on 

 leaves ; some infest the bodies of insects ; and others, as 

 the cheese-mite, live in cheese and other provisions. If 

 you have a microscope, and get from a cheesemonger a 

 little of the dust which has been shaken out of the cracks 

 in rather dry cheese, you will be surprised to see that 

 what seemed to your unassisted eye merely very fine dust, 

 lying perfectly still on a piece of paper, as dust would do, 

 becomes, when under the microscope, a mass of life : 

 hundreds and thousands of well-armed animals, such as 

 you will see in the annexed drawing (Fig. 95), ranged in 

 battle array, fighting furiously, and all about some tiny 

 scrap of cheese or some of their empty egg-shells. This 

 will afford you much amusement, and you will admire the 

 wonderful construction of such minute creatures. 



Scorpions (Fig. 96) are at once known by their 

 formidable/^/* or feelers, which are so large that they 

 resemble the pincers of Lobsters and Crabs. They run 

 very quickly, and strike their prey with the hook at the 

 end of their body. This sting has several openings under 



* Palpo, I touch (Latin). 



