28 THE CLASS OF INSECTS. 



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

 mouth. The maxilla consists of a basal joint, or cardo^ 

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

 footstalk ; the 'pulpifer, or i)alpus-bearer ; and the lacinia, or 

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

 uryan. The lacinia is more membranaceous than the other 

 l)aits, and its upper surface is covered with tine hairs, and 

 Ibi-ms a great part of the side of the mouth. It is divided 

 into two lobes, "the superior of Avhich is caHed the galea, or 

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

 stitf hairs, and is used as a palpus in the Orthoptera and many 

 Coleoptera. The inferior lobe is attached to the internal angle 

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

 densely covered with stout hairs. The maxillary jyaJpi are 

 long, slender, one to four-jointed organs. In Peiia I have found 

 that both pairs of palpi bear organs probaljly of smell. 



The maxilhe vary greatly in the different groups. Their office 

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

 aid the maudiJL)les in comminuting it before it is swallowed. 

 This function reminds us of that of the tongue of vertebrate 

 animals. 



The lahimn, or secovd maxillw (Fig. 40), is placed in front of 

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

 a on each side by the genw, or cheeks, and 

 posteriorly by the occiput. The gense are 

 bounded laterally by the epicranium and 

 the under side of the eyes. In front are 

 situated the basal parts of the labium, or 

 second maxillfe, which embraces the siihvientum and mentum 

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

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

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

 Dr. Lccontc (Smithsonian Miscellaneous Collections) the ligula, 

 and from which the pal^)! originate. The ligida is the front 

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

 It is often a Heshy organ, its inner surlace being continuous 



Fig. 40. Ligula and labial palpi of Amphizoa, an aquatic beetle. It is quadrate 

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

 tooth at the bottom of the excavation. — From Ilvrn. 



