7 6 



a whole should be carefully examined before the parts are 

 dissected out. 



In the study of the mouth-parts of insects the student 

 should bear in mind that the labrum, although in position 

 and use actually one of the mouth-parts, differs morphologic- 

 ally from the mandibles, maxillae and labium in not being a 

 modified pair of head appendages. 



Labrum. The labrum is short and broad, and is immov- 

 ably fused with the clypeus. 



Epipharynx. Directly underneath the labrum is the well- 

 developed elongate strap-like epipharynx. It is fleshy and 

 membranous and bears numerous, spiny hairs. 



Mandibles. The mandibles are large and toothed. When 

 they are closed one overlaps the other to a considerable 

 extent. 



Maxillse. The maxillae, although of the generally simple 

 character of the biting type, show some rather confusing 

 modifications. The cardo is strongly chitinized, distinct, 

 rather large and subclavate in shape. The stipes is large, 

 strongly chitinized and is (like the stipes of the beetle's 

 maxilla) partly divided into three sclerites, from one of which 

 rises the small, slender, six-segmented palpus. The terminal 

 lobes assume a peculiar character, the distinctly two-seg- 

 mented galea being large and flat, and bearing many papillar 

 hairs. From the large basal segment of the galea there rises 

 a distinct, flattish lobe also bearing many long papillar hairs. 

 Make a drawing of a maxilla. 



Labium. The labium is a complex organ in which, how- 

 ever, the typical composing parts can be pretty readily dis- 

 tinguished. The submentum and mentum are fused to form 

 a large strongly chitinized, bent, basal sclerite. This scle- 

 rite is bent so as to present a strongly convex under (outer) 

 surface, and a deeply concave upper (inner) surface. This 

 deep concavity or furrow is filled, with the fleshy and mem- 



