EXTERNAL ANATOMY OF INSECTS. 44] 
most important part of the organ, since it is that which 
often acts upon the food, when preparing for deglutition. 
When armed with teeth or spines at the end, its sub- 
stance is as hard as that of the mandibles; but when not 
so circumstanced, it is usually softer, resembling leather, 
or even membrane*; and sometimes the middle part is 
coriaceous, and the margin membranous. ‘This part is 
either simple, consisting only of one lobe, as you will 
find to be the case with the Hymenoptera, Dynastida, 
Nemognatha, and several other beetles; or it is com- 
pound, consisting of two lobes. In the former case, the 
lobe is sometimes very long, as in the bee tribes, and the 
singular genus of beetles mentioned above, Nemogna- 
tha; and at others very short, as in Hister, &c. The 
bilobed mazille present several different 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 (Goerius olens)*. 
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 tetradactyla)’. A third is 
where the upper lobe covers the lower as a shield; as 
you will find in the Orthoptera order, and the Libelluli- 
na, and almost in Meloe*. <A fourth form is where the 
* In Anoplognathus, however, though it has neither teeth nor 
spines, it is as hard as the mandibles. 
' See above, p. $15. 
er EATE RAVI: Bre, 10, 1 ld: e!'. 4 Tbid. Fic. 9. d!". el”, 
© Prater VI. Fie. 6,12. d. e”. Oliv. Ins. no. 45. Melo. t. i. 
f. 1. c. These are what Fabricius calls galeate maxille, on which he 
founded his class U/onata, 
