NO. 2 HONEY BEE SNODGRASS 51 



surface of the hind wing, and the hooks of the latter become engaged 

 in the fold of the former (E). 



The fore zmng. — The mesothoracic wing of the bee is much larger 

 than the hind wing (fig. i8) and has a stronger and more elaborate 

 venation. The four veins that arise at the base of the wing are 

 probably costa (A, C), fadiits (R), iiiedia-cubifus (MCii), and an 

 anal, or vannal, vein (A). It is difficult to identify the branches of 

 these main veins in the coarse reticulation of the distal part of the 

 wing, but it will not be necessary for a study of the wing mechanism ; 

 an understanding of the basal structure of the wing, however, is of 

 much importance. 



The base of the fore wing is overlapped by a large scalelike lobe 

 known as the tegula (figs. 15, 19 A, Tg), which is flexibly attached 

 to the margin of the scutum just before the wing. In the wasp 

 Vespiila Duncan (1939) finds a small depressor muscle of the tegula 

 arising on the scutum, but the writer has observed no muscle con- 

 nected with the tegula in Apis. 



In the naturally extended position of the fore wing, the wing base is 

 rolled on itself (fig. 19 A), the posterior part being turned downward 

 so that little of it is visible when viewed from above. If the basal 

 region is artificially spread out flat (D) the posterior part is seen to 

 be an extensive area widening toward its attachment on the body. 

 The whole region of the wing base presents at first sight a confusion 

 of small irregular parts, some of which are expansions of the wing 

 veins and others independent sclerites in the basal wing membrane. 

 A closer study, however, soon shows that there is an orderly arrange- 

 ment of the parts and a mechanical interrelationship between them, 

 which latter becomes more evident when the wing is moved. 



The anterior part, or humeral area, of the wing base (fig. 19 D) 

 is occupied by a large irregular sclerotization, here termed the humeral 

 complex because it appears to include parts derived from the bases of 

 the first three veins and also a remnant of the subcosta, which is 

 suppressed in the distal part of the wing. The posterior part of the 

 wing base, or axillary area, contains several discrete sclerites, which 

 are the first, second, third, and fourth axillaries {lAx, 2 Ax, ^Ax, 

 jAx), and a prominent, transversely elongate medicin plate (in). All 

 these sclerotizations are held in a basal wing membrane, bordered 

 posteriorly by a corrugated marginal thickening known as the axillary 

 cord (AxC), which is continuous on the one hand with the posterior 

 margin of the wing, and on the other with the lateral extremity of 

 the scutellum of the mesonotum (F, J, AxC). 



