ITS OUTER SKELETON. 



43 



The reference of these to a common plan, and the determina- 

 tion of the constituent parts, is mainly the work of Savigny. 

 Mouth-parts were made the basis of the classification of Insects 

 by Fabricius (1745-1808). 



MTI 



Fig. 20. The Jaws, separated. Mn, mandible, seen from behind (to left) and front 

 (to right) ; Mx l maxilla (first pair) ; Mx n labiuni, or second pair of 

 maxilla?. The other letters as before. X 20. 



