264? SYSTEMATIC ARRANGEMENT. 



to the extremity. The sheath, or external articulated 

 portion, is formed hy the elongation of the labium or 

 lower lip, and is liable to little variation, except in 

 length. Savigny seems to regard the basal segment 

 alone as representing the true lip. It encloses four 

 slender hair-like pieces, dilated a little at the base, 

 and finely denticulated at the extremity. Of thes 

 the superior pair represent the mandibles, and the 

 others the two blades of the maxillae. They are 

 incapable of horizontal motion, and the latter are 

 destitute of the jointed appendages which they always 

 bear in masticating tribes.* Over the base of the 

 rostrum is situate the labrum or upper lip, of a coni- 

 cal shape, and usually very much lengthened, pointed, 

 and frequently transversely striated. Immediately 

 beneath this is sometimes observed another piece of 

 similar form, which Latreille regards as analogous to 

 the epipharynx, and also another portion which should 

 be considered as corresponding to what he calls the 

 hypopharynx. The clypeus is frequently distinct 

 and conspicuous ; the reverse is the case with the 

 lingua or tongue, although Savigny has occasionally 

 detected its presence. 



The anterior part of the head is sometimes very 

 much produced, forming a long beak, occasionally 

 furnished with spinous projections. This is the case 

 with the Fulgorae, and in a well known species of that 

 tribe, it is inflated into a large mitre-shaped appendage 

 of a very remarkable appearance. 



* Faint traces of palpi are said to have been observed in 

 Thrips and Nepa. 



