146 
BRITISH APHIDES. 
Different degrees of oxydation of tlie nourishing 
fluids of the animal may partly account for such 
changes as are connected with climatal action. A 
reduced vitality may induce chemical changes, just 
as we find that chlorophyl, the colouring matter of 
green leaves, will pass through the stages of xantho- 
phyl and erythrophyl to the black tints of decay. 
The integuments of Aphides are so thin and trans- 
parent, that they readily show the colours of the 
viscera they contain. Again, the numerous oil-globules, 
to be found more particularly in the vicinity of the 
cornicles, are often beautifully coloured, and these 
materially increase the rich tinting of the bodies 
of Aphides. These hues, however, must not be con- 
founded with such characteristic marks and distinct 
bands as are due to the precipitation of pigment within 
the tissues. 
With the exception of blue, I think Mr. Walker gives 
every colour to A urtica. I have little doubt that the 
Aphis I here name A. carnosa is included amongst 
these varieties. Yet A. iirticce is a larger insect, the 
antennse are disproportionately long, the wings are 
narrower, the thoracic lobes are more pronounced, and 
the abdomen is spotted laterally. These points, coupled 
with the difference in colour, make me think myself 
justified in separating this insect from A. urticce of 
Passerini and other authors. 
As the ferruginous tint is peristent throughout the 
summer, I do not ascribe its presence to the action of 
a low temperature. 
Yotice will hereafter be taken of the investigation 
of the colouring matter of some Aphides by Mr. Sorby, 
who studied the absorption lines brought into view by 
the spectroscope. 
. SiPHONOPHORA LONGiPENNis, BucUon. Plate XX (bis). 
Apterous viviparous female. 
Form, long oval ; much attenuated towards the tail. 
