ARTHROPODA 



17 



There are three pairs of legs, each thoracic segment l^earing one pair 

 (Fig. 1). The leg is divided into five articulated parts, — coxa, trochanter, 

 femur, tibia, and tarsus. The attachment to 

 the bod}' is by the short coxa, to which is joined 4, 

 the trochanter which is also short. Following •'^Cr^<f7^'~>r~>''~^ 

 the trochanter are two long segments, — the fe- v ^ 



mur and tibia, the former considerably thicker fig. 3.— Diagram of In- 

 than the latter and contaming the muscles. The sect's Heart: c, constriction 



tarsus, or foot, follows the tibia, and consists of between two chambers; V, 

 ', „ , , , , • valves (after Boas, bj' Kirk- 



a number ot short segments, the last bearmg aidy & Pollard), 

 hook-like structures, or claws. 



Usualh' there are two pairs of wiiigs arising dorsally from the meso- 



FiG. 4. — Mouth-parts of Locust, a biting insect: Labruni, or upper-lip, 

 above, on each side of which are the mandibles, or upper pair of jaws. 

 Labium, or under lip, with labial palpi below. Ma.xillae, or lower pair of 

 jaws, with maxillary palpi, to right and left (from photomicrograph of 

 mounted specimen, by Hoedt). 



and metathorax (Fig. 1). They consist, when fully developed, of two 

 closely apposed chitinous outgrowths, between which are extensions of 



