ANATOMY AND PHYSIOLOGY. 77 
There are a pair of mandibles which meet’ in the © 
middle line working transversely, and which are said 
to represent the upper jaw. And, lastly, there are a 
pair of maxille, which are said to represent the 
lower jaw, which have a free movement in every 
direction, and lie concealed behind the mandibles. 
These will all require a separate examination. 
The larger size of the hornet renders her the most 
convenient subject for examimation; and for the 
study of the hard horny parts perhaps a dried speci- 
men is the best. If we carefully examme the trun- 
cated angle of the clypeus on its lower edge, we shall 
find, closely connected to the back of it, a small 
crescentic horny flap, having a leaf-like projection 
from its centre. This is the labrum, or upper lip, 
which lies immediately behind the line in which the 
mandibles meet, and closes the cavity of the mouth 
above. It is much larger and more distinct exter- 
nally m the honey-bee than in the wasp, but it still 
retains the character of a simple membranous flap, 
armed perhaps with bristles, but with no secondary 
organs such as we find on the lower lip. 
The mandibles are at once to be recognized, 
occupying the lower part of the face beneath the 
clypeus. In the Solitary group they are long, and 
run out into a beak as they meet each other in the 
middle line; or they overlap like the mandibles of 
the crossbill. This form and arrangement is almost 
peculiar to the Solitary group, and differs widely 
from that found in our Wasps, which have short, 
strong mandibles, ending, not in a point, but in a 
serrated edge, resembling rather a half closed paw, 
or the claw of a dentist’s key, than the bill of a bird. 
