i'.")<> PTILOTA: IMAGO EXTERNAL ANATOMY. 



In many insects, however, it is quite membranous, and is in 

 such cases completely concealed by the clypeus, with which, 

 indeed, it was sometimes confounded by Fabricius, who also 

 gave to it the name of that part. It is generally fringed with 

 hairs. In some few Hymenoptera it is furnished with a slen- 

 der appendage, to which indeed Illiger applied the name of 

 labrum. In the Hemiptera the upper lip is in the form of an 

 elongate triangle, which falls upon the base of the canal of 

 the lower lip (fig. 8!), / 1). In the Lepidoptera it is so 

 minute as not to be discernible without great care, appearing 

 as a small triangular piece extending downwards towards the 

 base of the labial palpi (fig. 87, M). In the Diptera it is 

 either obsolete, or exists in the shape of a corneous, slender 

 gutter, hollowed beneath, and receiving the other slender 

 lancet-like organs (fig. 88, / 1). 



The Mandibles, or upper jaws (m in the figures). These 

 organs, in the generality of biting insects, are the chief 



Figs. 65. Mandible* ufTher.tr.-96, ditto of Hybomm-97, ditto Mlmrl. UN, ditto (,,,iriu. 



instruments by which the food is bitten into pieces. They 

 have been considered analogous to the jaws of the higher 

 animals, but they have a much greater resemblance to a pair 

 of large and robust, horny, and notched teeth. They are 

 inserted at the sides of the oral aperture, immediately below 

 the lower lip, to which, indeed, they appear to bear the same 

 kind of relation as the lower jaws do to the lower lip. They 



