22 



THE ANATOMY OF THE , HONEY BEE. 



basal joint called the coxa {Ox). Beyond this is a smaller joint 

 called the trochanter {Tr), this is followed by a long and strong 

 segment, the fem/tir (i?"), which extends outward from the body, while 

 bending downward from its distal end is the long and slender tibia 

 (Tb), followed finally by the foot, or tarsus (Tar). The tarsus itself 

 consists typically of five small segments of which the last bears a pair 

 of cluws (Cla). The under surfaces of the tarsal joints are often 

 provided with small cushions or pads called ptilviUi. Those between 

 the claws are generally specially prominent and are called the 

 empodia {Emp). The leg varies greatly in shape in different in- 

 sects but usually preserves all of these parts. The segments of the 

 tarsus, however, are frequently reduced in number. 



The adult wing is a thin expanse of memhranc sujjported by hollow 

 branching rods called i^eins. It originates as a hollow outgrowth of 

 the body-wall, but soon becomes flattened out dorso-ventrally and the 



Fig. 6. — Diagram of generalized insect wing and its articulation to first plate (A') of 



the tergum, 



contained trachess or air tubes mark out the courses of the veins. 

 These veins form various j)atterns in different insects, but they can all 

 be derived by modification from one fundamental plan. This plan is 

 shown diagrammatically by figure 6. The first vein, which usually 

 forms the anterior margin of the adult wing, is the casta ( G) . The 

 next vein is the subcosta {Sc), which in typical cases divides into 

 two branches {Sc^ and 8c^). The third and usually the principal 

 vein is the radius {R). It divides dichotomously into five branches 

 {R^ to R^), the anterior branch of the first fork remaining single. 

 The next vein is the media (M), which forms four branches {M^ to 

 yl/4). The fifth is the cubitus (Cu), which again is two-branched. 

 The remaining veins are called the anaJs and are designated indi- 

 vidually as the first anal (lA), second anal {^A), etc. 



Several cross-veins of common recurrence should be noted. The 

 first is situated near the base of the wing between the costal and 

 subcostal veins and is known as the humeral cross-vein. A second 



