HEAD APPENDAGES 157 



To see the next three pairs of appendages, fix the animal 

 down on its back by means of a pair of small pins passed 

 through the sides of its prothorax. Bend the ventral part of 

 the head forwards and fix it in that position by means of 

 crossed pins. 



Examine the appendages in situ, noting their positions. 



Remove the whole of the labium (s M to P G,fig. 29) without 

 injury to the structures beneath it. Mount it in glycerine. 



Similarly remove and mount the right first maxilla and 

 the right mandible. 



b. The mandibles are a pair of stout jaws, strongly 



toothed on their inner margins, and working side- 

 ways. They lie immediately below the genae, 

 and articulate with the epicranium and with the 

 clypeus. 



c. The first maxillae are situated behind the mandibles. 



Each consists of the following parts. 



i. The protopodite consists of two joints, the cardo 

 or proximal piece, and the stipes or distal 

 piece. 



ii. The endopodite has two divisions, an inner and an 

 outer. The inner division, or lacinia, is a hard 

 blade with stiff setae along its inner border, 

 and pointed at the end. The outer division, or 

 galea, is softer and is elongated : on the inner 

 surface of its distal end is an oval cushion 

 covered with short curved stiff setae, and 

 notched to receive the point of the lacinia. 



iii. The exopodite or maxillary palp is a five-jointed 

 palp, borne on the outer side of the distal end 

 of the stipes. Its first two joints are short. 



d. The second maxillae are similar in shape to the first 



maxillae, but smaller. They are fused together 

 in the median plane by their protopodites, and 

 together constitute the labium or posterior lip. 



