66 INTRODUCTION TO ZOOLOGY. 



The centipede is a very active and a very vicious 

 little creature. The usual way of catching one is to 

 seize it quickly with the fingers as soon as the stone is 

 turned over. In stich a case, the centipede tries to 

 bite, and frequently succeeds. No poisonous effects, 

 however, have ever been experienced by the writer, 

 who must have been bitten a hundred times. The 

 large centipede of the southwestern states, Scolopendra, 

 is two or three times as long as the Scolopocryptops, but 

 resembles it closely in every structural respect. 



The maxillipeds are remarkable organs. They are 

 located on a .segment behind the head. They are 

 jointed. In both position and structure, they agree 

 with the legs. They must be homologous to legs. But 

 they work sideways, like jaws, and are used as jaws. 

 The jaws (mandibles) have the same position they do. 

 So we must conclude that maxillipeds are homologous 

 to jaws. But by the axiomatic proposition that things 

 which are homologous to the same thing are homolo- 

 gous to each other, the mandibles of a centipede 

 must be homologous to the legs of a centipede. But 

 the mandibles of a centipede are clearly homologous 

 to the mandibles of a grasshopper. Therefore it seems 

 clear that the mandibles of a grasshopper are homolo- 

 gous to the legs of a grasshopper. We may illustrate 

 the homologies by a diagram : — 



Therefore, etc. 



