NO. 2 HONEY BEE SNODGRASS 65 



backward position at the sides of the abdomen. Each leg has char- 

 acteristic features, and, in the worker particularly, various parts of 

 the legs are developed into specific structures for special uses. 



For descriptive purposes it is customary to name the leg surfaces 

 according to the positions they assume when the limb is extended 

 straight out from the body. In such a position the upper surface is 

 dorsal, the under surface ventral, the preaxial surface anterior, and 

 the postaxial surface posterior. The actual directions of the leg 

 surfaces in normal positions, however, may be quite different. 



Inasmuch as the legs differ principally in relative size, form, and 

 outer structure, the general external features will be described 

 separately for each pair, while the mechanism of the joints, and the 

 muscles, which are but little different in the three pairs of appendages, 

 will be treated collectively in order to avoid unnecessary repetition. 



The fore legs. — The fore legs (fig. 13 A) are smaller than the 

 others and have somewhat less freedom of motion because of the 

 vertical position of the coxae (fig. ii G), but, in compensation, the 

 femur of each fore leg has an anterior twist (fig. 14 A) by which the 

 tibia acquires a forward movement, and, when fully flexed, lies 

 against the anterior surface of the femur and trochanter. The long, 

 cylindrical, bristly first tarsomere is used as a brush for removing 

 pollen or other particles from the head and fore parts of the body, 

 but the most important special features of the first leg is the antenna 

 cleaner at the base of the tarsus. 



The antenna cleaner (fig. 14 B) consists of a deep semicircular 

 notch (&) on the inner (ventral) face of the proximal end of the 

 basitarsus (Btar), and of a large flattened spur (a) that serves as a 

 clasp, or fibula, projecting from the inner angle of the distal end of 

 the tibia (Tb). The posterior margin of the notch bears a comblike 

 fringe, or pecten, of fine, closely set, spinelike hairs. The fibula is a 

 broad, thin, movable appendage with a narrowed base, a tapering 

 distal point, and a strong, spatulate accessory lobe {e) on its anterior 

 surface. When the tarsus is flexed by the depressor muscle (E, (58) 

 the proximal lobe of the basitarsal notch (C, c) glides under the 

 accessory lobe {e) of the fibula, and the distal point of the tarsal 

 notch {d) is caught in the angle between the two fibular lobes. The 

 tarsal notch is thus closed to a semicircular aperture by the accessory 

 lobe (?) of the fibula, and the larger flat lobe (a) overlaps the aper- 

 ture posteriorly. When the organ is used by the bee, the tarsal notch 

 is placed around the base of the antennal flagellum by movements of 

 the leg, and then, by flexion of the tarsus, the antenna is pressed 

 against the accessory lobe of the fibula, which latter resists the 



