168 
BRITISH APHIDES. 
want this tooth, they cannot belong even to the same 
genus as P. humuli. 
There is some difficulty in deciding on this point 
of identity. Koch says that his Aphis malaheb is 
closely related to A, humuli^ but that it wants the 
projecting branch on the first root-joint (ersten 
Wurzelglied) which distinguishes that species/^^ by 
which I understand him to mean that the first antennal 
joint is not toothed. On the other hand, Passerini,t 
from reasons above given, excludes Malaheb from 
Phorodon, and places it in his genus Myziis. 
Once more, Kaltenbach considers Aphis malaheb of 
Koch to be a variety of A, pruni of Boyer de Fonsco- 
lombe. Thus Koch and Passerini decide differently 
from Kaltenbach and Walker. 
I incline to the opinion of the latter authors, and 
therefore I figure it as a variety only. The difference, 
which, however, is not small, appears chiefly in the 
younger individuals of the apterous females. 
For comparison I have figured these parts of the 
head and antennse in their various stages of develop- 
ment, and here I add a description of P. malaheb^ which 
I regard as a variety. 
Phorodon humuli var. malaheb, Fonsc. Plate XXXI, 
figs. 1 — 4. 
Aphis pruni^ Fonscolombe. 
„ malaheb, Koch. 
Myzus malaheb, Pass. 
Apterous viviparous female. 
Indies. 
Size of body 0*110 X 0*052 
Length of antenn.^ 0*070 
„ cornicles 0*030 
Millimetres. 
2-79 X 1-30. 
1-77. 
0-76. 
* ‘ Die Pflanzenlause Apliiden/ von 0. L. Kodi, p. 113. 
f Vide “ Fiora degli Afidi Italiani finora osservati,” ‘ II Biillettino 
Entomologico/ Anijo III, al§o ‘ Zoologist ’ for MarcL, 1862, p. 1122, 
