44 
DESCRIPTION OF SPECIES. 
In this part of my report the sub-families, tribes and genera will be 
arranged systematically according to the plan I have adopted; but no 
attempt will be made to arrange the species systematically, as I have 
not had an opportunity of examining sufficient material tor this pur¬ 
pose. There are a few species introduced on the authority of other 
authors which I am unable to locate with certainty, not having seen 
specimens, these will be placed where they appear to belong with 
notice of the uncertainty in reference to their proper position. 
Sub-Family APHIDINAE. 
This sub-family includes all the species possessing the following 
characteristics: The front wings with three discoidal veins, exclusive 
of the fourth or stigmatic vein at the apex; the third discoidal vein is 
twice forked (see Fig. 9) in all the species known, except those be¬ 
longing to the genus Toxoptera where it has but a single fork (see 
Fig. 10); the posterior wings have two oblique or branch veins; antennae 
Fig 9. Fig. 10 - 
six or seven-jointed, the latter number being more usual than the for¬ 
mer; the third joint longer than the fourth, fifth or sixth, and usually ] 
as long or longer than the seventh; the seventh generally setaceous j 
and in many species as long or even longer than the third. Reproduc¬ 
tion viviparous and oviparious; the oviparous female always apterous; j 
all the species as far as known producing at some time winged in- . 
dividuals, (at least all those included as I have here arranged this j 
group.) The number of species belonging to this division is very large, 
being the most extensive group in the entire family. On this ac¬ 
count entomologists have endeavored to split up the old. genus Aphis , 
which corresponded with this sub-family, into more limited genera. 
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