62 THE ANATOMY OP THE HONEY BEE. 



Taking this wing of Sirex as a foundation let us proceed a little 

 higher and examine the wing of a Pompilid, such as Pepsis (figs. 

 26 C and 25 B). We observed that in Sirex (fig. 26 B) the basal 

 part of vein Sc is almost separated from the distal shaft. In Pepsis 

 (fig. 26 C) it is entirely a separate piece, to which is fused also the 

 base of vein E. Moreover, the shaft of Sc has disappeared entirely 

 (fig. 25, B). Thus there is at the humeral angle of the wing a large 

 chitinous mass (fig. 26 C, Sc and R) representing the fused bases 

 of both the subcosta and the radius, which is associated with 

 both the first axillary (lAx) and the second axillary {2 Ax). 



If now we proceed to a study of the front wing of the bee we 

 find that its basal characters (fig. 26 F) are more similar to those of 

 Sirex (B), while its venation (fig. 25 C) resembles more closely that 

 of Pepsis (B). The subcostal scale at its base (fig. 26 F, Sc) is 

 not fused with the base of the radius, but the distal part of the 

 subcosta is gone (fig. 25 C), as in Pepsis. In the hind wing of the 

 bee (fig. 26 H) the bases of the subcosta and radius are fused into 

 one large humeral mass articulating with the first two axillaries 

 {lAx and £Ax). The third axillary {3 Ax) is well developed but 

 the fourth is absent. The venation (fig. 25 D) is reduced to a very 

 simple condition, but to one just the opposite from primitive. 



The details of the axillaries in the two wings are shown by figure 

 26 D and G. The fourth {4^ix) is well developed in the front wing 

 (D) and has a large accessory sclerite (y) connected with it, upon 

 which is inserted a long slender muscle (fig. 28, cc). A very small 

 accessory sclerite (ax) occurs close to the muscle plate of the third 

 axillary {3Ax). These are called "accessory" sclerites because 

 they are of irregular occurrence in the wing bases of insects generally 

 and are developed in connection with the muscle attachments. Simi- 

 lar ones occur in the hind wing (G, ax) in connection with the 

 second {2 Ax) and third axillaries {3 Ax). 



The front wing is attached to the posterior half of the side of 

 the mesonotum. The anterior notal wing process is bilobed (figs. 

 22, 23 A, ^2, ANP) and is carried by the scutum, while the pos- 

 terior process {PNP) is carried by the scutellum and is mostly 

 hidden beneath the anterior wing process. The two wing processes, 

 in fact, are so close together that the first axillary articulates not 

 only with the first but also with the second (fig. 26 J). The axillary 

 cord (fig. 26 F, AxG) arises from a lobe of the scutellum overlapped 

 by the lateral margin (I and J, AxC). In the hind wing, where the 

 fourth axillary is absent, the third articulates directly with the 

 posterior notal wing process of the metatergum (fig. 23 A, T'j, PNP). 



The base of the front wing is overlapped by a large scale (fig. 26, 

 E and I, Tg) called the tegula. It is carried by the axillary mem- 



