PHYLUM ARTHROPODA 



333 



modified for special functions. Those of the honey-bee have 

 already been described (pp. 314 and 316, Fig. 238). A typical 

 leg consists of five parts, coxa (Fig. 238, B, c), trochanter (tr), 

 femur (/), tibia (//), and tarsus (/). The tarsus (Fig. 239) is 

 usually composed of five segments and bears at the end a pair 

 of claws (an) , between which is a fleshy lobule, the pulvillus (pv) , 

 Figure 254 shows a number of legs adapted for different uses. 

 Running insects possess long, slender legs (b) ; the mantis (a) 

 has its fore legs fitted for grasping; the hind legs of the grass- 

 hopper (c) are used in leaping; the fore legs of the mole cricket 



FIG. 255. The right wing of a male mosquito, Anopheles maculipennis. 

 A, anal area; ist A, anal nervure; C, costa; Cu, cubitus; H, humeral cross- 

 nervure; 7, cross-nervure between R* and /?4+s; /, cross-nervure between 

 radial and medial systems; A', cross-nervure between medial and cubital sys- 

 tems; M, media; 0, cross-nervure between 7?i and Ri; R, radius; Sc, sub- 

 costa. (From Sedgwick's Zoology, after Nuttall and Shipley.) 



(d) are modified for digging; and the hind legs of the water 

 beetle (e) are fitted for swimming. Many other types could be 

 mentioned. 



The wings of insects enable their owners to fly rapidly from 

 place to place and thus to escape from enemies and to find a 

 bountiful food supply. The success of insects in the struggle for 

 existence is in part attributed to the presence of wings. Wings 

 are outgrowths of the skin strengthened by a framework of 

 chitinous tubes, called veins or nervures, which divide the wing 

 into cells. The veins vary in distribution in different species, 

 but are quite constant in individuals of any given species; they 

 are consequently used to a considerable extent for purposes of 

 classification. The principal longitudinal veins, as shown in 

 Figure 255, are the costa (C), subcosta (Sc), radius (R), media 



