10 



COLEOPTKRA OF INDIANA. 



Fig. 2. Maxilla of 

 Harpnlus caliginosus. 

 (After Smith.) 



Olio consists of two basal pieces and three outer pnrts. The first or 

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

 us(h1 to hint>'e the other parts of the niaxilhe to the 

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

 ''ardt) nsnally at a more or less acute angle, and 

 forms a i)laee of snpport for the onter parts. These 

 (onsist (if two 1()h( s and one nia.nlJarji palpus. The 

 lo])es vary nnich in form and sometimes one or the 

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

 the galea, is often slender and divided into two 

 joints like a palpns. The inner lobe, known as the 

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

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

 and often nsed ;is brnshes by pollen-eating beetles. The maxUlari) 

 palpus (i)lnral palpi) arises from an upper segment of the stipes, 

 called the paJpif'cr. The palpi are nsnally 4-jointed, rarely 3- 

 jointed (in the genns AhocJiara alone o-jointed). The joints vary 

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

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

 oval or sub(|nadrate, more often triangular or hatchet-shaped. 

 When suddenly narrowed and more slender than the preceding, the 

 palpi are said to l)e subulate or awl-shaped. The development and 

 shape of the maxilla^ 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 rendering the food more suitable for swal- 

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

 cases act as hands in pi'chending and carrying morsels of food to the 

 mouth. 



The floor of the uK^ith beneath and between the maxilla' is 

 formed of two small pieces called the ni< nfuni and the lahiuiit. The 

 mentum is joined to the gula or throat, which is the region behind 

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

 1\ire. The mentum varies greatly in form and size and is often 

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

 emargination. When deeply notched tlie side-pieces are called lobes. 

 The labium is usually in fi-ont 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 iKu-n-like in tex- 

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



