Mr. F. Walker^s Descriptions 0 / Aphides. 453 
as almost to form a tubercle on each segment : the fore-chest is 
large : the middle chest is rather shorter : the hind-chest and the 
following segments are much shorter and of nearly equal size : 
the feelers are slender, almost filiform, pale green at the base, 
brown at the tips, and less than one-third of the length of the 
body : the eyes are brown ; the mouth is dull green : the nectaries 
are yellow, and about one-twentieth of the length of the body : 
the legs are dull green, long and stout ; the feet are brown. In 
the middle of April on the shoots of the willow. 
1st variety. Dull olive-green, varied with browm. 
The viviparous winged female. The wings of this fly are un- 
folded before the middle of May : it is metallic black, and shghtly 
covered with gray powder : the fore-breast and the underside of 
the abdomen are grayish green, and the back of the latter has 
alternate bands of black and gray : the feelers are black, slightly 
setaceous, and hardly half the length of the body ; the fourth 
joint is much shorter than the third ; the fifth is a little shorter 
than the fourth ; the sixth is shorter than the fifth ; the seventh 
is a little longer than the sixth : the mouth is dull green with a 
darker tip, and reaches a little beyond the base of the hind-legs ; 
the eyes are black : the nectaries are orange and extremely short : 
the legs are black, long and stout ; the thighs towards the base, 
and the shanks except their tips are dark red : the wings are 
colourless, and longer than the body ; the wing-ribs are pale 
yellow ; the wing-brands are long, and dull buff ; the veins are 
brown ; the rib-vein does not widen into the brand, but passes 
along its hind-border ; the first and the second veins are nearly 
straight ; the third is obsolete at its source, and is inclined in- 
wards, and forms two very slight obtuse angles where it throws 
off its forks ; the first fork begins soon after one-third, the second 
soon after two-thirds of the length of the wing : the legs are 
rather stout, and long, and hairy. 
Length of the body 2 lines ; of the wings lines. 
Thirteenth Group. 
Containing one species which seems to be always wingless. 
25. Aphis Salicivora, n. s. 
The viviparous wingless female. The body is oval, flat, hairy, 
and yellow : the hairs on the sides of the body are very long : the 
front is hairy and slightly convex, and has no tubercles : the 
feelers are slender, setaceous, and nearly as long as the body ; the 
fourth joint is much shorter than the third ; the fifth is fully as 
long as the fourth ; the sixth is shorter than the fifth, and in- 
creases in breadth from the base to the tip ; the seventh is much 
