246 SYSTEMATIC ZOOLOGY. 



I 



long, wingless animals which feed upon the oak and which, 

 as they stand motionless upon a twig can scarcely be dis- 

 tinguished from the twigs themselves. The species figured 

 is foreign. 



Grasshoppers and locusts are much alike, and are usu- 

 ally confused by most people. Both are leaping forms, 

 but the locusts have short antennae and short ovipos- 

 itors, while the grasshoppers have these parts long. The 

 katydid is a grasshopper, while the ' grasshopper' which 

 in 1873-76 did much damage in our western states is a 

 locust. Closely allied are the crickets, whose ceaseless 

 chirp is so monotonous upon summer nights. These make 

 their song by rubbing their wing-covers together, and it is 

 interesting that only the male can make the noise.* The 

 1 ear ' of the cricket is not upon the abdomen but upon the 

 for'e legs. It is not certain that any of these structures 

 are really for hearing. 



ORDER III. PSEUDONEUROPTERA. 



These forms, like the Orthoptera, have biting mouth- 

 parts, and have a gradual change from the young to the 

 adult, but they differ from those forms in having both 

 pairs of wings alike, usually very thin, and transparent, 

 with very numerous veins, and not capable of being folded 

 like those of the Orthoptera. There are two divisions of 

 these Pseudoneuroptera. In the first the younger stages 

 are passed in the water, in the second on land. 



Examples of the first are seen in the dragon-flies 



* It has been pointed out that the number of chirps of the crickets 



is dependent upon temperature, and that in the northern states 



n 40 



the temperature can be ascertained by the formula T = 50 -| ^ , 



in which T stands for temperature and n for the number of chirps 

 per minute. 



