PART I 



ARTHROPODA: SEGMENTED FORMS WITH 

 JOINTED LEGS 



1. ORTHOPTERA 



THE majority of the species of animals belong to the 

 branch Arthropoda. A feature distinguishing this group 

 from all other invertebrates is the presence of jointed legs. 

 These, however, may be absent in a few forms leading a 

 parasitic life (Fig. 150) . Of the four classes of Arthropoda, 

 the insects, numbering over three hundred thousand 



FIG. 6. A, Long-horned grasshopper; B, Locust; a, antennae; o, ovipositor. 



species, are the most important because among them are 

 found man's greatest enemies as well as valuable helpers. 



Locusts 



The locusts, commonly called grasshoppers, include about 

 three hundred different species, but only three or four kinds 

 are easily found in any one locality. Only the short-horned 

 30 



