COLEOPTEEOTTS INSECTS. 103 



immediately behind it, which may be considered 

 as forming its base, is named the chin (mentum). 

 This piece is usually transverse, or broader than 

 long, and is in most instances sinuated or notched 

 in the middle of its anterior edge, with an acute tooth 

 in the centre of the notch, which is sometimes bi- 

 fid. From each side of the labium, and frequently 

 attached to its lateral margin, there projects an ar- 

 ticulated feeler, similar to those borne by the max- 

 illae. These are called the labial palpi. They ge- 

 nerally consist of three moveable articulations, at- 

 tached to a fourth which is adherent and forms a 

 support to the others. They seldom equal the ex- 

 ternal maxillary palpi in length, and the terminal 

 joint does not exhibit such a variety of form, being 

 most commonly somewhat clavate, or nearly of equal 

 breadth throughout its whole length. 



The most conspicuous appendages of the head 

 are two jointed organs, which stand out like horns 

 from the forehead, and are named antenna. These 

 never exceed two in number in genuine insects, and 

 are situated anterior to and rather beneath the re- 

 gion of the eyes : occasionally they are placed close 

 to the margin of the eyes, and in some instances the 

 latter have a sinuosity for their reception, and par- 

 tially encompass their base. They are generally 

 composed of eleven obconical or tubular joints, lia- 

 ble to great variation in their relative proportions. 

 Occasionally, however, the joints do not exceed 



