378 



THE WORLD OF ANIMAL LIFE 



the name of Chilopoda, and the millipedes into another class 

 entitled the DiPLOPODA. Through these forms we arrive at the 



class Arachnida. 



ARACHNIDA 



Most people, if they were asked what a Spider is, would reply 

 that it is a kind of insect. But this would be a mistake, for 

 spiders are not insects according to scientific classification. 



The frame of an insect, as we have seen, is divided into three 

 parts, which we have called the head, the chest, and the body. 

 The frame of a spider, however, is divided into two parts only, 



the head and chest 

 ^' being united. 



All insects have 

 six legs, although 

 two of these are 

 sometimes not fully 

 developed. Spiders, 

 however, always have 



eight 



legs. 



Some- 



Gai'den Spider, i, Male; ;.::, female 



times these legs are 

 very long, sometimes 

 very short; but as a 

 Spiders, moreover, 



rule we can see and count them quite easily, 

 never have wings. 



There is a great difference, also, between the eyes of spiders and 

 those of insects. Insects, as we know, have two great eye-masses, 

 one upon either side of the head. Each of these is composed of 

 a great number of separate eyes, which are mostly six-sided in 

 form, like the cells of a honey-comb. A common house-fly has no 

 fewer than four thousand of these eyes, while a well-known English 

 butterfly has between seventeen and eighteen thousand! 



But a spider has only eight eyes at the most, and these are 

 situated, not at the sides of the head, but upon its upper surface. 

 By examining the head of a spider we can easily see these eyes. 



