OR, MANUAL OF THB APIARY. 79 



second row, from the front or costal edge of the primary wings, 

 called the sub-costal cells. Thus, in the genus Apis there are 

 three such cells (Fig. 2—6, 7, 8), while in the Melipona there 

 are only two. The ribs or veins consist of a tube within a 

 tube, the inner one forming an air-tube, the outer one carrying 

 blood. On the costal edge of the secondary wings we often 

 find hooks (Fig. 2, h) to attach them to the front wings. 



The wings are moved by powerful muscles, compactly 

 located in the thorax (Fig. 25), the strength of which is very 

 great. The rapidity of the vibrations of the wings when flight 

 is rapid, is almost beyond computation. Marey found by his 



Fig. 26. 



Hairs of Bees. — Original. 



ingenious and graphic method that they number in the bee 190 

 in a second. This may be far from the maximum. Think of 

 a tiny fly out-stripping the fleetest horse in the chase, and 

 then marvel at this wondrous mechanism. 



The legs (Fig. 1, g, g, g) are six in number in all mature 

 insects, two on the lower side of each ring of the thorax. 

 These are long or short, weak or strong, according to the habit 

 of the insect. Fach leg consists of the following joints or 

 parts : The coxa (Fig. 67, cf, which moves like a ball-and- 

 socket joint in the close-fitting coxal cavities of the body- 

 rings. Next to this follow in order the broad trochanter (Fig. 

 67, T,) which is double in several families of Hymenoptera like 

 the very valuable ichneumon and chalcid flies, the large, broad 

 femur (Fig. 66, F), the long, slim tibia (Fig. 67, 7"), frequently 

 bearing strong spines at or near its end, called tibial spurs, 

 and followed by the from on^ to five jointed tarsi (Fig. 67, 1, 

 2, 3, 4, S). All these parts move freely upon each other, and 

 will vary in form to agree with their use.. At the end of the 



