CLASSIFICATION OF INSECTS. 253 



move horizontally ; the telum is armed with seta, 

 and the body covered with hairs or scales. This 

 class contains two orders. 



824. Lepismites (Lepismites). Antennae very 

 long, composed of a great number of joints, often 

 more than forty; the telum is furnished with 

 three long setae, composed, like the antennae, of 

 many joints ; it is not capable of being bent under 

 the insect. Forhicina, Petrobius, Lepisma. 



825. Spring-tails (Porfwntes). Antennae shorter, 

 never apparently composed of more than four 

 joints, although the last has numerous rings, which 

 may, perhaps, be considered joints by some : the 

 telum is furnished with two setas, and is bent 

 under the body, giving an amazing saltatory 

 power to the insect. Podura, Smynlhurus. 



826. In the second class {Anoplura) the mouth 

 appears very imperfect ; in one order there are 

 mandibles with an horizontal motion, in the other, 

 they are elongate, rigid, and united ; the telum is 

 not furnished with appendages. The insects com- 

 posing the class are entirely parasitical on other 

 animals. This class contains two orders. 



827. Lice {Pediculites). Mouth with the 

 mandibles and other parts united, and forming a 

 short blood-sucking tube : the animals composing 

 this order are found on the bodies of mankind, 

 dogs, pigs, cattle, &c. Phthirus, Pedkulus, 

 Hcematopinus. 



828. Bird-lice (Mrmi<M). Mouth with distinct 



