GENERIC CLASSIFICATION OF APHIDIDAE. 23 
cies described as Symydobius albasiphus by Davis and here placed as 
Neosyrnydobius. 
The internal structure of insects of this tribe appears not to differ 
markedly from the structure in other groups. Witlaczil, however, has 
reported that in certain members of this tribe the intestine forms a 
closed loop almost similar to that found in the Chermidae. 
As a rule, in this tribe, the various forms met with in the subfamily 
occur. In the genus Monellia, however, in some species at least, ap- 
terous viviparous forms seldom occur, nearly all the viviparous forms 
being alate. 
The sub tribes may be separated by the following key: 
Key to the Subtribes op the Callipterini. 
1. Eyes with ocular tubercles present, head not elongate 2. 
Eyes without ocular tubercles present, head-often elongate Saltusaphidina." 
2. Antennae armed with rather long, prominent hairs 3. 
Antennae usually only with minute, sometimes stout bristles 5. 
3. Cornicles absent Fullawayina. 
Cornicles present 4. 
4. Cornicles cylindrical or vasiform Pterocommina. 
Cornicles truncate, enlarged at base Chaitophorina. 
5. Cornicles absent above Monaphidina. 
Cornicles present, position as usual 6. 
6. Cornicles reduced to mere rings; large lateral abdominal wax plates 
present Phyllaphidina. 
Cornicles usually not reduced to mere rings; no large abdominal wax plates 
present 7. 
7. Cornicles variable, often long and somewhat swollen; oviparous female 
with an elongate ovipositor Drepanaphidina. 
Cornicles never long; always short and truncate; oviparous fem?le not always 
with an elongate ovipositor Callipterina. 
Subtribe PHYLLAPHIDINA. 
The subtribe Phyllaphidina is erected for the species related to the 
genus Phyllaphis. Many of the characters show these species as 
quite closely related to the Callipterina, while in other ways they very 
strongly suggest the Thelaxini, as indicated under the discussion of 
the tribe. 
Characters. — Cornicles present; antennae of six segments, minutely setose, sensoria 
elongate or subcircular; cauda knobbed or rounded, anal plate often bilobed, wax 
glands present. Forms living free or in pseudogalls. Sexual forms often alate, some- 
times, however, apterous or intermediate, showing that the apterous condition has 
developed but recently; oviparous female producing several eggs. 
Key to the Genera op the Phyllaphidini. 
1. Anal plate deeply cleft and U-shaped Shivaphis. 
Anal plate entire or somewhat bilobed, not deeply cleft 2. 
2. Cauda rounded, anal plate entire 3 . 
Cauda knobbed, anal plate somewhat bilobed Phyllaphis. 
3. Oviparous females with annular sensoria Neophyllaphis. 
Oviparous females with small transverse sensoria Tamalia. 
