278 ELEMENTARY ENTOMOLOGY 



2. Mandibles. These lie directly beneath the labrum and con- 

 sist of a pair of short, thick pieces. The inner edge is somewhat 

 flattened and provided with a number of toothlike projections 

 which form the grinding surface of the mandibles. 



3. Maxillae. These are the second pair of jaws ; they lie directly 

 beneath the mandibles and are much more complicated in struc- 

 ture. After they have been removed and mounted in glycerin, 

 the following parts can be distinguished : 



a. The car do. This forms the attachment or basal piece of the 

 maxilla, and is triangular in shape. 



b. The stipes. This is a quadrangular-shaped segment forming 

 the central part of the maxilla. One side is attached to the cardo, 

 and two of the other sides form the attachment for the remaining 

 structures. 



c. The lacinia. This is attached to the inner edge of the 

 stipes, and is a long, curved piece terminating in a row of sharp 

 teeth. 



d. The galea. This portion of the maxilla articulates with the 

 stipes on its outer edge, just below the attachment of the lacinia. 

 It closely resembles this latter structure, except that the end is 

 rounded instead of being toothed. 



e. The maxillary palpi. These arise from a basal portion 

 known as the palpifer, which articulates with the stipes between 

 the attachment of the galea and the cardo. The palpi consist of 

 five long, slender segments, and, like the antennae, are sensory in 

 function. 



4. Labium. The labium, or under lip, forms the under part of 

 the mouth and, together with the upper lip, almost incloses the 

 mandibles and maxillae. The labium is a complicated structure 

 made up of the following parts : 



a. The submentum. This forms the attachment to the epicra- 

 nium and is a crescent-shaped piece. It is also joined to the 

 membrane which connects the head with the thorax. 



b. The mentum. This is the central portion of the labium, and 

 is joined to the distal margin of the submentum. 



c. The ligula. The ligula consists of two large, movable flaps 

 attached to the distal, or outer, edge of the mentum, and forms 

 the terminal, central portion of the labium. 



