456 EXTERNAL ANATOMY OF INSECTS. 
from the mandibles and labrum. In the former case, the 
mandibles coincided at the base, the two molary plates 
(mole), which in this genus are narrow, transverse and 
not furrowed, are so applied as evidently to have an 
action upon each other, as the mandible opens and shuts, 
proper for trituration. Within these is the base of the 
tongue, under the form of a ventricose sack. The upper 
part of this last organ, which forms the internal covering 
of the labium, appears to consist of three (in the recent 
insect fleshy) lobes, the middle one being bent down- 
wards internally, so as to form a kind of sloping cover 
to an orifice in the part I call the base. After two or 
three days, the tongue shrinks and dries to a hard sub- 
stance ;—between the mandibles and the base of the 
tongue I could not discover the pharynx. The above 
apparent opening covered by the tongue was the only 
one I could perceive. In the latter case, the form and 
structure of the base of the tongue is more visible: it 
is an oblong ventricose tubular sack, projecting above 
anteriorly into an acute angle formed by a fine white 
membrane, most beautifully and delicately striated with 
oblique striae, to be seen only under a powerful lens : 
on the anterior side of this sack are two parallel carti- 
laginous ridges close to each other, fringed with short 
hairs, which take their origin from the angle. I could 
not be certain whether the orifice covered by the in- 
termediate lobe was only apparent, or real; but I did 
not succeed in my endeavour to find any other pha- 
rynx, though from the molary structure of the base of 
the mandibles one may conjecture that there must be one 
situated at the base of this sack to receive the food they 
render after trituration. The excrement of this animal 
