28 THE CLASS OF INSECTS. 



iiiserteu on the under side of the head and just behind the 

 month. The maxilla consists of a basal joint, or cardn. 

 beyond which it is subdivided into three lobes, the stipes, or 

 footstalk ; the i><tlj'f(>r, or palpus-bearer: and the laciitia, or 

 blade. The stipes forms the outer and main division of the 

 organ. The laeinia is more membranaceous than the other 

 parts, and its upper surface is covered with tine hairs, and 

 forms a great part of the side of the mouth. It is divided 

 into two lobes, the superior of which is called the (jalea, or 

 helmet, which is often a thick double-jointed organ edged with 

 stiff hairs, and is used as a palpus in the Urthoptera and many 

 Coleoptera. The inferior lobe is attached to the internal angle 

 of the laeinia. It terminates in a stiff minute claw, and is 

 densely covered with stout hairs. The nui.i-i/}r>/ palpi are 

 long, slender, one to four-jointed organs. In P<',ia I have found 

 that both pairs of palpi bear organs probably of smell. 



The maxilhv vary greatly in the different groups. Their oflice 

 is to seize the food and retain it within the mouth, and also to 

 aid the mandibles in comminuting it before it is swallowed. 

 This function reminds us of that of the tongue of vertebrate 

 animals. 



The lb!nm. oi' <<<< >n<l /iid.n'llft' (Fig. 40). is placed in front of 

 the (jnhi. which forms the under part of the head, and is bounded 



ou each side by the <jcn\ or cheeks, and 

 posteriorly by the occiput. The gena* are 

 bounded laterally by the epicraniuni and 

 ^^^^ the under side of the eyes. In front are 



situated the basal parts of the labium, or 

 second maxilhe, which embraces the subim-nttim and mention 

 (or labium proper). The labial palpi are inserted into the 

 mentum, but often the latter piece is differentiated into two. 

 the anterior of which takes the name of jHiIjiif/a; called by 

 Dr. Leconte (Smithsonian Miscellaneous Collections) the ligula, 

 and from which the palpi originate. The liyula is the front 

 edge of the labium. being the piece forming the under lip. 

 It is often a fleshy organ, its inner surface being continuous 



FIG. 40. Ligula and labial palpi of Amphizon, an aquatic- beetle. It is quadrate 

 and without paraglossw ; , meiitmn of the same, being deeply incised, and with a 

 tooth at the bottom of the excavation. /Vow Horn. 



