EXTERNAL ANATOMY. 



EXTERNAL ANATOMY/ 



The body of a locust consists of an external thick skin, 

 hardened and stiffened b^' a substance called chitine, which 

 protects the softer organs within. Chitine is a peculiar 

 substance found only in the teguments of articulated ani- 

 mals. The harder external skin is the analogue of the skele- 

 ton of the mammalia, and to it are fastened all the muscles 

 that are necessary for the functions of an insect. As this 

 oviter skeleton must be more or less rigid, insects would not 

 be able to move at all if it were not jointed or segmented in 

 such a manner that each segment, or ring, is connected with 

 the neighboring ones by a softer membrane. Each segment 

 may be again subdivided into smaller pieces. We can observe 



Ist pair of Legs 



Ist pair of \ying3 

 2n(l pair of Legs 



2nd pair of Wings 



3rd pair of Legs 



Head 



■=-^--;^^ iTIior.nx 



Abdomen 



Tarsus •-- ../fpiS^'; 



i--^^. 



Fig. 21. — A locust dissected to show divisions of body. 



such segments quite readily in caterpillars ; the abdomen of 

 the locust also shows them very distinctly, as here the seg- 



*See explanation of anatomical illustrations at end of chapter. 



