EXTERNAL ANATOMY OF INSECTS. 417 
strictly considered, it will be found that in this view they 
ought rather to be regarded as forming three tribes; for 
the great majority of the Hymenoptera order, and per- 
haps some others, though furnished with mandibles and 
maxillz, never use them for mastication, but really lap 
their food with their tongue: these, therefore, might be 
denominated /appers. 
When a mouth is furnished with the seven ordinary 
organs used in taking the food and preparing it for de- 
glutition—I mean the upper-lip and the two upper-jaws; 
the under-lip and the two under-jaws, including the la- 
bial and maxillary palpi; and the tongue—I denominate 
it a perfect mouth ; but when it is deficient in any of these 
organs, or they exist merely as rudiments, or when their 
place is supplied by others, (which, though they may be 
analogous parts, have little or no connection with them 
in their use or structure,) I denominate it an zmperfect 
mouth. ‘This last I would further distinguish, according 
to the nature of its ¢rophz, by other and more distinctive 
terms, as I shall presently explain to you. 
1. Labrum*.—I shall first consider the organs pre- 
sent in a perfect mouth, beginning with the upper-lip (Ja- 
brum). This part, which Fabricius sometimes confound- 
ed with the nose, miscalling it clypeus, is usually a move- 
able? piece, attached by its base to the anterior margin 
of the part last named, and covering the mouth, and 
sometimes the mandibles, from above. In insects in 
their last state it is usually of a horny or shelly substance ; 
yet in some cases, as in Copris and Cetonia, beetles that 
* Prares VI. VII. XXVI. a’. 
>In Lucanus, Lamprina, &c. the labrum seems to form the under- 
side of the nose, and to be connate with it. 
VOL. [II. Diy 
