84 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



lAx- 



secondary tegula, but it can not be confused with this organ, because 

 the tegula is present also and overlaps the subcostal scale. 



In the hind wing the bases of the subcosta and radius are generally 

 fused into one large humeral mass, as shown in Tremex columba 

 (71, Sc and R), Apis meUifera (72), and Leucospis affinis (73). 



The details of the axillaries of Tremex columha and of Apis mellifera 

 are shown by figure 19. The first axillary (lAx) always articulates 

 with the anterior wing process of the notum (fig. 8, ANP), while 

 its anterior neck articulates with the base of the subcostal vein. 

 The second axillary {3Ax) rests below upon the wing process of the 

 pleurum and is associated with the base of the radial vein. Its inner 



edge articulates with the body of 

 the first axillary and its poste- 

 rior end is usually articulated to 

 the third. A muscle disk (fig. 

 19, A, B, AxD) or some sort of 

 muscle-bearing sclerite is usu- 

 ally attached to its posterior end 

 by a long tendon-like stalk and 

 carries the upper end of the slen- 

 der coxo-axillary muscle, whose 

 lower end is attached to the up- 

 per rim of the coxa of the same 

 segment. The third axillary 

 (SAx) is associated with the 

 bases of the anal veins and car- 

 ries the insertion of the flexor 

 muscles of the wing. It nearly 

 always presents a special lobe for 

 the accommodation of these 

 muscles and is often provided 

 with an accessory sclerite (fig. 19, 

 B, C, Sax). The fourth axillary 



lAx 



nAx. 



AxD 



Fig. 19.— Axillary sclerites; A, of front wing of 

 Tremex columba; B, of hind wing of Tremex 

 columba; C, of front wing of Apis mellifera; 

 D, of hind wing of Apis mellifera: lAx, first 

 axillary; $Ax, second axillary; SAx, third 

 axillary; Sax, accessory sclerite of third axil- 

 lary; 4Ax, fourth axillary; AxD, disk of 

 coxo-axillary muscle attached to second 

 axillary; y, muscle-bearing sclerite attached 

 to fourth axillary of front wing in Apis 

 mellifera. 



(4.Ax) is always smaller and sim- 

 pler than the others. It is present in the front wing of most of the 

 Hymenoptera and in the hind wing of many of them. It is gen- 

 erally absent in other insects except the Orthoptera. When pres- 

 ent, it forms the hinge plate of the wing articulating with the pos- 

 terior wing process of the notum (fig. 8, PNP). It is absent in the 

 hind wing of Apis (72 and fig. 19 D) and in the hind wing of Leu- 

 cospis (73). In these cases the third axillary (SAx) is associated with 

 the posterior wing process. In the honey bee the fourth axillary of 

 the front wing has a large accessory sclerite (70 and fig. 19 G,y) asso- 

 ciated with it, upon which is inserted a slender muscle attached to an 

 arm of the sternal furca. 



