THE COCKROACH : 



In Hemiptera the long- four-jointed labium (Lm) forms a 

 sheath for the stylets. When not in use the whole apparatus 

 is drawn up beneath the head and prothorax. The mandibles 

 (IMii) are sharp at the tip, and close like a pair of forceps, en- 

 closing the maxillae (lAr). These are of unequal length, only 

 one reaching the end of the mandibular case. Both have saw 

 teeth on the free edge. Palps are entirely wanting. 



Lbr 



Fig. 26. Mouth-parts of Bug. Copied from 

 Landois, Zeits. f. wiss. Zool., Bd. XVIII. , 

 taf. xi., fig. 3. 



Fig. 26A. Diagram of Mouth-parts 

 of Bug. 



Comparing the four kinds of suctorial mouths, of which the 

 Bee, the Moth, the Fly, and the Bug furnish examples, we 

 observe that the sucking-tube is formed in the Moth out of the 

 two maxillae, in the other three out of the labium. Of these 

 last the Bee has the edges of the labium turned down, so that 

 the siphon becomes ventral ; in the Bug and Fly the edges 



