98 
Dr. T. A. on Callophrys avis. 
difficulty of finding tlie cast heads. A circumstance that 
adds mucli difficulty to counting the moults. 
When the young (first instar) larva of G. ruhi attains its 
colour, ■which it does a shade earlier than does G. avis, the 
colours are not pale ochreous green and brown, but a 
white that is almost that of porcelain and a more ochreous, 
less red, brown. The dorsal brown lines are broader. 
The white below it looks broader and perhaps is, but its 
greater effect is more due to its whiteness, aud to its 
wanting the brown patch on each segment, the sub¬ 
dorsal hairs (ill ?) are visible with a hand lens easily, 
being black as are the lateral (llange) hairs (colourless 
in avis). 
In the last instar, the uniform green tint of G. avis con¬ 
trasts in its light transparent tone with that of G. rubi 
(Plate XV), in the same stage, and in its uniformity, quite 
unbroken by any trace of the oblique stripes, which are 
always more or less present in G. rnbi. Any appearance 
of stripes in G. avis is the effect of the illumination on 
the irregularities of the “ upholstering ” of the sides. 
G. avis has its yellow lateral line and its red mark across 
the prothorax, but no other colouring, aud each larva is 
like every other without any variation. G. rubi always 
has the oblique stripes, sometimes as a different tone of 
green, sometimes as more or less bright yellow, and 
sometimes further emphasised by some red margins, 
making a very handsome and gaudy larva. I did not 
meet with this brilliant form this year, so have not got it 
figured. An essential point, moreover, is not merely the 
j)resence of these stripes in some form, but the great 
range of variation that the larva presents, as compared 
with the uniform G. avis. It never has any approach to 
the red thoracic mark, and may even seem almost without 
a thoracic plate; the mark here in G. rnbi being merely 
the very small central brownish portion of the plate, 
Avithout any further colouring. 
Another marked difference between the two ' species in 
the last instar, is the much greater dorsal swelling of the 
segments and the correspondingly greater depth of the 
nicisions dorsally in G. rubi. So that on lateral view, 
G. rubi has a very serrate dorsal outline, as compared 
with the tolerably smooth aspect of G. avis, the latter 
might, in I'act, wlien compared with G. rubi, almost be 
taken for a Chrysophanid like G. rutihis. 
