334 Mr. F. Walker’s Descriptions of Aphides. 
are undeveloped as is usual in wingless Aphides, but in other cha- 
racters it resembles the winged female. The body and the kgs 
are bristly : the front is slightly convex in the middle, and has a 
tubercle crowned with a tuft of bristles on each side : the body is 
nearly spindle-shaped and often appears quite full of young ones : 
the feelers are as long as or longer than the body ; the fourth 
joint is very much shorter than the third ; the fifth is a little 
shorter than the fourth ; the sixth is about half the length of 
the fifth ; the seventh is nearly as long as the fifth ; the tips of 
the joints from the third to the sixth are brown : the fore- legs 
are not much shorter than the hind-legs ; the shanks are straight : 
the nectaries are about one-twentieth of the length of the body. 
A variety of this form has the body quite round, and pale yel- 
low : the limbs are white : the feelers are longer than the body ; 
the fourth joint is as long as the third ; the fifth is a little longer 
than the fourth ; the sixth is more than half the length of the . 
fifth ; the seventh is much longer than the fifth ; the tips of some 
of the joints are black : the legs are very slender and rather short. 
Another variety has much stouter legs than usual. 
The viviparous winged female. This feeds on the leaves of the 
birch-tree [Betula alba) from J uly to October, but is more scarce 
than Aphis Betulce : its colour is bright yellow, and its back is 
slightly hairy : the forehead has a slight protuberance on each 
side : the feelers are yellow, slender, and much longer than the 
body j the tips of the joints are brown ; the third joint is very 
long j the fourth is much shorter than the third ; the fifth is a 
little shorter than the fourth ; the sixth is slightly clavate, and 
about one-third of the length of the fifth; the seventh is as long 
as the sixth : the eyes are dark red : the mouth is yellow ; its tip 
is brown : the nectaries are extremely short, and not more than 
one-twelfth of the length of the body : the legs are yellow, long 
and slender ; the feet, the knees, and the tips of the shanks are 
brown : the wings are colourless ; the wing-ribs, the wing-brands 
and the veins are tawny ; the tips of the latter are slightly clouded ; 
the first and second branch-veins are more perpendicular to the 
rib-vein than in most species of this genus ; the first is thick ; the 
fourth is obsolete except at its tip. 
The length of the fore-chest is not less than its breadth ; its sides 
are convex : the legs are very slender ; the shanks are slightly 
curved : the main vein begins at three-fourths of the length of 
the wing to widen into the wing-brand which is irregularly spin- 
dle-shaped ; the fourth vein is obsolete except at its tip ; the third 
vein is obsolete at its source, and is forked before one-thii’d of 
its length and forked again before two-thirds of its length ; the 
branches of the forks, and especially of the second fork, diverge 
rather abruptly from each other; the second vein is rather per- 
