122 



GENERAL ZOOLOGY 



pair of claws. The abdomen is provided with a sting at its 

 extremity. The whip-scorpion (Thelyph'onus), also found in 



similar situations in the South, 

 is another formidable -looking 

 creature, with immensely devel- 

 oped maxillse, which are used 

 to pull open decaying wood in 

 search of small insects, which 

 form its food. Its appearance 

 accounts for the dread it in- 

 spires, but there is no evidence 

 to show that it is harmful to 

 man. 



Definition of Arachnida (Gr. 

 arachne, spider). All the forms 

 considered so far in this chapter 



FIG. 65. Photograph of Scorpion, belong to the class Arach'nida. 

 Natural size. (American Museum The Arachnida a^ree in having 

 of Natural History) , , ., , fo . 4 



the somites iused into two more 



or less clearly marked regions, the cephalothorax and the 

 abdomen. There is no distinct head, as in insects. Eight 

 legs are present. The Arachnida undergo no well-marked 

 metamorphosis. 



Centipeds. The common centiped (Litho'bius, Fig. 66) found 

 under the bark of trees is an elongate, flattened animal, 

 with long antennae, many somites, and a pair of legs on every 

 somite. There is a poison-gland in the base of the first pair 

 of legs, which is used to kill earthworms and insects, upon 

 which Lithobius feeds. The female is furnished with two 

 hooks at the end of the body close to the oviduct. When an 

 egg is laid it is seized by these hooks and rolled over till it 

 is completely covered with earth, which adheres to the egg 

 on account of a sticky substance with which it is covered. 

 It has been observed that if a male Lithobius perceives the 



