28 THE CLASS OF INSECTS. 



inserted en the under side of the head and just behind the 

 mouth. Tlie maxilla consists of a basal joint, or cardo, 

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

 footstalk ; the iialpifer, or palpus-bearer ; and the lacinia, or 

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

 organ. The lacinia is more membranaceous than the other 

 parts, and its upper surface is covered with fine 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 galea, or 

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

 >stiff hairs, and is used as a palpus in the Orthoptera and manj" 

 Coleoptera. The inferior lobe is attached to the internal angle 

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

 densely covered with stout hairs. The maxillary palpi are 

 long, slender, one to foiu'-jointed organs, ver}' flexible and sen- 

 sitive. 



The maxillae vary gi-eatly in the different groups. Their office 

 is to seize the food and retain it Avithiu 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 labium, or second maxilla; (Fig. 40), is placed in front of 

 the gida, which forms the under part of the head, and is bounded 

 a on each side b}" the gence, or cheeks, and 

 posteriorly b}' the occiput. The genje are 

 bounded lateralh' by the epicranium and 

 the under side of the ej-es. In front are 

 Fig. 40. situated the basal parts of the labium, or 



second maxillse, which embraces the submentum and mentinn 

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

 mentum, but often the latter piece is dirterentiated into two, 

 the anterior of which takes the name of palpiger, called by 

 Dr. Leconte (Smithsonian Miscellaneous Collections) the ligula, 

 and the palpi originate from them. The ligula is the front 

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

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



Fig. 40. Ligiila and labial palpi of ^»ip7»soa, an aquatic beetle. It is quadrate 

 and Avithout paragloss»; a, mentum of the same, being deeply incised, and with a 

 tooth at the bottom of the excavation. — From Hoi-n. 



