10 COLEOPTERA OF INDIANA. 



one consists of two basal pieces and three outer parts. The first or 

 lower one of the former is called the cardo, and is 

 nsed to hinge the other parts of the maxilla; to the 

 head. The second, the slipes, is jointed to the 

 ' ardo usually at a more or less acute angle, and 

 forms a place of support for the outer parts. These 

 lonsist of two lohcs and one maxillarxj palpus. The 

 lobes vary much in form and sometimes one or the 

 other is so small as to be indistinct. The outer one, 

 narvoLia^^ "' the gdra, is often slender and divided into two 

 (After Smith.) joints like a palpus. The inner lobe, known as the 

 lacinin, is more or less jaw-like and its inner margin is armed with 

 flexible or stitf bristles, spines or teeth which are variable in form 

 and often used as brushes by pollen-eating beetles. The viariUarij 

 I'dlp-us (plural palpi) arises from an upper segment of the stipes, 

 called the palpifer. The palpi are usually 4-jointed, rarely 3- 

 jointed (in the genus Alcochara alone 5-jointed). The joints vary 

 greatly in size and form and are therefore much used in classifica- 

 tion. The fourth one is most varialile, sometimes being broad and 

 oval or subquadrate, more often triangular, or hatchet-shaped. 

 When suddenly narrowed and more slender than the preceding, the 

 palpi are said to be subulate or awl-shaped. The development and 

 shape of the maxilkv of beetles, as of other insects, depend very 

 largely upon the nature of the food, as those organs serve not only 

 to seize and hold the food in the mouth, but also as accessory jaws, 

 aiding the mandibles in I'endering the food more suitable for swal- 

 lowing. Their palpi are not only organs of touch, but in many 

 eases act as hands in prehending and carrying morsels of food to the 

 mouth. 



The floor of the mouth beneath and between the maxilla^ is 

 formed of two small pie; es called the iitfiifitni and the lahunn. The 

 nientum is joined to the guhi or throat, which is the region behind 

 or below the mouth, the suture between them being the mental sti- 

 inrr. The mentum varies greatly in form and size and is often 

 notched cr emarginate in front, with a tooth at the middle of the 

 emargination. When deeply notched the side-pieces are called lohes. 

 The labium is usually in front of the mentum or in the notch 

 between the lobes; rarely it is almost entirely hidden. It is com- 

 posed of three parts, a central piece, the ligula. and two side-pieces 

 called the paraglossa. The labium is often wholly horn-like in tex- 

 ture, in which case the paraglossa are not distinct. In such case the 



