28 TIIK CLASS OF IN SHOTS. 



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

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

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

 footstalk; the pa/j'j'<-r. or palpus-bearer; and the /m-////a, or 

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

 organ. The lacinia is moie membranaeeoiis than the other 

 l>;nts, and its upper surface is covered with line 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 </ttl<<<i. or 

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

 stiff 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 stiff minute claw, and is 

 densely covered with stout hairs. The maxillary polpi are 

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

 that both pairs of palpi bear organs probably of smell. 



The maxillae vary greatly in the different groups. Their office 

 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 lubiiim, or second maxitttv (Fig. 40), is placed in front of 

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

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

 r\ r\ posteriorly by the occiput. The geme are 

 v ) bounded laterally by the epicranium and 



I 1 the under side of the eyes. In front are 



situated the basal parts of the labium, or 

 second maxilla 1 , which embraces the nl>n'ii1inn and nn-nfimi 

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

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

 the anterior of which takes the name of jui/jiii/fr. called by 

 Dr. Leconte (Smithsonian Miscellaneous Collections) the ligula, 

 ami from which the palpi originate. The lif/trtd 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 



FlG. 40. Lijrula and labial jialpi of ,tmi>hi:ti. an aquatic beetle. It is quadrate 

 and without panijrloss.T ; a, nientum of .the same, beiujr deeply incised, and with a 

 tooth at the bottom of the excavation. J-'roni ll<-rn. 



