208 



INTRODUCTION TO ZOOLOGY 



labium or " lower lip," which bounds the mouth on the lower 

 side. The labium also bears a pair of processes known as the 



Fig. 1.39. — The Mandible, Maxillae, and Labium of a Cockroach. 

 mnd, mandible ; a & has been removed from a' b' ; mx, maxilla ; TtixUs, maxillary 

 lobes ; mx.palp, maxillary palp ; m, mentum bearing the labial palp, Lp, and 

 the labium, Lb. The central lobe of the labium, the lingua, can be faintly seen. 



labial palps, and attached to it is a central lobe known as 



the lingua or tongue. 



In different insects, with different feeding habits, these 



various mouth-parts be- 

 come modified to suit the 

 food in each case, but 

 always the same parts can 

 be recognised, namely, 

 the single upper lip 

 (labrum), the pair of hard 

 jaws (mandibles), the 

 pair of soft jaws (first 

 maxillae), and the lower 

 lip, or labium, with its 

 palps. 



Of all the 



""^nsfor^'^Pe^-l «truc- 

 tures found 

 in insects, the most 

 peculiar and wonderful 

 are perhaps the large 

 compound eyes, which 

 are present in all adult 

 insects, although simple 

 eyes may also occur. 



Fig. 140.- 



-Section through the eye of a 

 Bee. 



o.n., Optic nerve ; 



I, lens ; c, cones ; r, rods ; 

 h, hair. 



