442 EXTERNAL ANATOMY OF INSECTS. 



The third and terminal portion of the maxilla is formed 

 by the lobe, or lobes (Lobi). This may be called the 

 most important part of the organ, since it is that which 

 often acts upon the food, when preparing for degluti- 

 tion. When armed with teeth or spines at the end, 

 its substance is as hard as that of the mandibles ; but 

 when not so circumstanced, it is usually softer, re- 

 sembling leather, or even membrane a ; and sometimes 

 the middle part is coriaceous, and the margin membra- 

 nous. This part is either simple, consisting only of one 

 lobe, as you will find to be the case with the Hymeno- 

 piera, Dynastidce, Nemognatha, and several other bee- 

 tles; or it is compound, consisting of too lobes. In the 

 former case, the lobe is sometimes very long, as in the 

 bee tribes, and the singular genus of beetles mentioned 

 above b , Nemognatha; and at others very short, as in 

 Hister, &c. The bilobed maxilla? present several diffe- 

 rent types of form. Nearest to those with one lobe are 

 those whose lower lobe is attached longitudinally to the 

 inner side of the stalk of the organ, above which it 

 scarcely rises. Of this description is the maxilla in the 

 common dung-beetle (Geotrupes stercorarius), and rove- 

 beetle {Staphylinus olens). c Another kind of formation 

 is where the lower lobe is only a little shorter than the 

 upper : this occurs in a kind of chafer (Macraspis tetra- 

 dactyla MacLeay). d A third is where the upper lobe 

 covers the lower as a shield ; as you will find in the Or- 



a |n Anoplognathus, however, though it has neither teeth nor 

 spines^ it is as hard as the mandibles. 

 b . See above, p. 317- 

 '«• 'Plate XXVI. Fig. 10, 11. d'". e"\ 

 J Ibid. Fig. 9. d". e"\ 



