418 THE AMERICAN NATURALIST. [VoL. XXXII. 
cross-vein. In the fore wing of the honey-bee (Fig. 43) veins 
R4 and R; still retain the appearance of branches of a forked 
longitudinal vein. 
In Pamphilius vein Rı is curved away from the costal margin 
of the wing to make room for a stigma (Fig. 39, S), and vein 
R, ends in the costal margin a short distance before the apex 
of the wing (Fig. 38). Vein 2 has been lost in this genus, 
but is well preserved in certain closely allied forms,! and is, 
therefore, represented in the figure. 
While the tips of the branches of the radial sector have 
migrated away from the apex of the wing, the bases of these 
Fic. 43. — Wings of Apis. 
branches coalesce in the opposite direction; from these two 
causes results the transverse bracing of the radial area of the 
wing, which is a very characteristic feature of the venation of 
the wings in this order. 
The details of these changes will be made clear by an exami- 
nation of Figs. 44 and 45. The former represents the primi- 
tive mode of branching of the radius; the latter, the radial area 
of the typical hymenopterous wing (Fig. 38). In the hyme- 
nopterous type veins Kz, 3 and 4+5 of the primitive type 
coalesce so far that the branches of the sector arise from a 
common stem; and the tips of all of them have moved away 
from the apex of the wing, veins R2 and FR; following the 
costal margin of the wing; and veins &4 and Rs following 
1 See p. 414, footnote. 
