338 Mr. W. Arnold Lewis on 
it; and in that year (as it is well understood, at his sug- 
gestion) Mr. Doubleday’s second List introduced the new 
arrangement. Let us bear in mind the important consi- 
deration that, in Mr. Doubleday’s List, the order of 
arrangement of the Nocrum was not changed. That 
remained the same as when the group followed next after 
the Bombyces, and the Geometre came at the end. Bom- 
byciformes is still the first section (including the families 
Noctuo-Bombycide and Bombycoide) ; and at the end 
come the various Quadrifide with their half-looping larvee 
(including the species acknowledged as Noctuo-Phalenidi 
by M. Guenée himself in 1841), 
It appears to me that this fact controlled the rest of 
the arrangement. The order of the Noctuc begs the 
question of the group’s position ; and it was, therefore, 
necessary to start the Noctue from somethimg Bomby- 
ciform. The new arrangement was introduced to give 
effect to the affinity between the Geometre and the Bom- 
byces, and this was carried out by placing the two groups 
in juxta-position. Now, if the Geometre had only 
been brought up and placed next to the Bombyces, the 
Noctue making way for them, would have had to follow 
the Geometre. The complete re-arrangement of the 
Noctue would then have become necessary in view of 
their changed location. But there were weighty reasons 
against proposing a re-arrangement of the Noctue. Not 
only had this group been long described in the books, in 
the order which it would be necessary to abandon; but 
M. Guenée himself had, within a very few years, com- 
pleted an exhaustive work, whose order of arrangement 
would also have become obsolete. M. Guenée would of 
course be disposed to see advantage in a plan, which, 
while giving full play to the affinity between Geometra 
and Bomby«, at the same time preserved and vindicated 
his own previous arrangement of the Noctuc. And here 
I think we find the reason of the existing order. 
It was necessary in the first place to join the Geometree 
to the Bombyces, in order to exhibit what in the new 
view was the natural relationship between these groups. 
But, to preserve the union of the Noctuce with the Bom- 
byces was equally necessary, if the existing arrangement 
of the former was to be upheld. These two objects 
were accomplished in the only way possible; and the 
steps by which they were accomplished were the natural 
ones for that purpose. 
