ARTICULATA. 



227 



carries a pair of spines. Sometimes the tail is curved 

 into a formidable poisonous hook, as in the Scorpion. 

 In temperate climates the Chilopoda are harmless, but 

 often dangerous in hot countries. Such is the Centipede, 

 (Scolopendra^} 



6. INSECTA. This class contains more species than 

 all the rest of the Animal Kingdom, 150,000 having 

 been already described. Its typical character is well 



FIG. 128. Diagram of Insect, (Blatta orientalist a. Head with compound eyes and 

 antennae, b. Prothorax with first pair of legs. c. Mesothorax with second pair of legs 

 and first pair of wings, d. Metathorax with third pair of legs and second pair of wings. 

 e. Abdomen without limbs, but carrying terminal appendages, which are subservient in 

 reproduction. 



marked, yet it contains a large number of instances of 

 special structure, arranged for evident purpose. Chap. 

 Ill, Sec. 9, and Chap. V, Sec. 6. 



The body is divided into three principal segments 



