INSECTA 



127 



The middle element of the thorax is the largest. The 

 nervature of the wings is utilised in insect classification 

 and is employed in 

 this group to dis- 

 tinguish the species. 

 Eight segments 

 visible in the 



are 

 ab- 

 domen, and the open- 

 ings are terminal. 

 The females only suck 

 blood, and it is 

 through them that 

 malaria is communi- 

 cated (p. 25). 



Malaria is com- 

 municated by species 

 of various genera 

 Anopheles, Cellia, My- 

 zomyia, Myzorhyn- 

 chus, Nyssorhynchus, 

 Pyretophorus. Ano- 

 pheles was once com- 

 mon in England, and 

 three species may 

 still be found. The 

 adults tend to be 

 common where the 

 conditions of water, 

 and habitation of 

 man, or of mammals 

 and birds, occur to- 

 gether. 



Another dipter- 

 ous genus, Glossina, 

 tsetse flies, has be- 

 come important from 

 the fact that it is the 

 means of introducing 

 the protozoan parasite 



Labium 

 Hypopfiarynx 

 Mandible 

 Maxilla 



Maxillary 

 palp 



Labrum- 

 epipharynx 



Antenna 



Ldbrum- 

 epipharynx 



Mandible 



Maxilla 



Labium Hypopharynx 



FIG. 60. Anopheles. Head appendages of 

 female, spread out and viewed from the 

 dorsal aspect. The transverse section of 

 the mouth parts (after Nuttall and Shipley) 

 should be compared with fig. 56. 



