INSECTA. 159 
present (fig. 78, 1): 1, An upper lip or “ labrum ” (2), attached 
below the front of the head. 2. A pair of biting-jaws (2) or 
“mandibles.” 3. A pair of chewing-jaws or “maxilla” (<), pro- 
vided with jointed filaments, called the “ maxillary palpi.’ 4. 
A lower lip or “labium” (@), which also carries a pair of jointed 
filaments, known as the “labial palpi.” In the typical suctorial 
mouth, as seen in the butterflies and moths (fig. 78, 2), the fol- 
ve 
Fig. 78.—Organs of the mouth in Insects. 1. Mouth of a masticating insect 
(beetle), represented diagrammatically : a Upper lip or ‘‘labrum; ” 3 Mandibles; 
¢ Maxillz, with their palpi; 2 Lower lip or ‘‘labium,” with its palpi. 2. Mouth 
of a butterfly: o Eye ; _/ Base of antennez ; ¢ Labial palp; % Spiral trunk. 3 
Mouth of a hemipterous insect: 7 Labium; 7 Maxillze ; 2 Mandibles. 
lowing is the arrangement of parts. The upper lip and man- 
dibles are quite rudimentary; the maxille are greatly lengthened, 
and form a spiral tube fitted for sucking up the juices of flowers ; 
and the labial palpi are much developed, and form two hairy 
cushions, between which the trunk can be coiled up when not 
in use. In many insects (fig. 78, 3) the organs of the mouth 
are essentially adapted for suction, but are also fitted for pierc- 
ing solid substances, such as the skin of animals or the stems 
of plants. In these the lower lip forms a kind of sucking-tube 
or sheath, within which are contained the maxillze and mandi- 
bles, which are modified so as to form piercing organs or lan- 
cets. In the common bee the masticatory and suctorial types 
of mouth are combined. The mandibles or biting-jaws are 
retained, ‘to enable the honeycomb to be manufactured, and 
there is also a tubular trunk fitted for sucking up the juices of 
