238 FIELD ZOOLOGY. 



which curve forward in front of the head, and make one's 

 fingers ache even to look at them. The body is dark 

 brown and rather heavily chitinized, even in the pre- 

 ' abdomen. The post-abdomen is much slenderer than in 

 the common scorpions. They destroy their prey by 

 crushing it in their powerful palpi; hence it would seem 

 that their sting is less a means of defense than is the sting 

 of the common scorpions. 



Spiders. 



Spiders are not insects, though they are closely 

 related to them. According to Comstock, the Arthropoda 

 are to be divided into the Crustacea, the Myriapoda, the 

 Hexapoda, and the Arachnida. The Crustacea include 

 the familiar crayfish, or "crawdads," and the lobsters, the 

 shrimps, and the crabs of our sea-coasts. The division 

 also includes the familiar pill bugs, light gray, round- 

 backed creatures with a shell covering the dorsal surface 

 of the body. They have numerous legs, and when they 

 are frightened they curl up in a ball, shell outward, looking, 

 as their name implies, like a shiny pill. They are found 

 in damp places, under the bark of old logs, near wood piles, 

 or under rotting boards. Their food seems to be decaying 

 wood or other vegetable substances. 



The Myriapoda have been seen to consist of the milli- 

 peds and the centipeds, The Hexapoda are the six- 

 legged Arthropoda or the insects; and the Arachnida, then, 

 would include the scorpions, true and false, the jointed 

 spiders, the harvestmen, mites and ticks, and the spiders. 

 The spiders differ from the insects not only in the possession 

 of an extra pair of legs, but also in the structure of the 

 body. The head is fused with the thorax, making the 

 cephalo- thorax, which is not segmented. The abdomen 



