26 
The variations in animals and plants are of great interest, 
and each contribution to the store of facts accumulated rela- 
tive to these variations, their causes and limits, is of value 
in determining the identity, and limits of species, in what- 
ever way we interpret the word species. Abraxas grossula- 
riata is probably one of the most variable insects we possess 
in this country, in colour and markings, and it would be 
quite pardonable in any one not well acquainted with it, 
were he to split it up into four or five species ; but although 
it varies in colour and markings in such a great degree, all 
these varieties are joined together by gradual steps, and yet 
no step is found to join it to the next species on our list, 
Abraxas ulmata. 
The larv® of this species will feed upon the leaves of 
most trees and shrubs, and is therefore easily experimented 
upon, as to whether the changes in food influence the colour 
or markings. So far as my own experiments, and I believe 
those of others are concerned, no difference whatever can 
be detected from the varieties of food, except in size. That 
long-continued changes of food through many generations 
might have a perceptible effect is however more than 
probable. 
The type form of this moth is too well known to require 
description. I will therefore exhibit a drawer of specimens, 
having the type form in the centre, the various forms 
radiating from it in steps, in one line ending in white, 
another in black, another in which the white ground runs 
gradually into brown, and various other marked varieties. 
We may divide these into the following seven groups : — 
1st variation. White, or the spots very few and distant : 
this leads up to the type form. 
2nd. Spots joined together, forming curves and lines. 
3rd. A variety of intermediate spots and patches. 
4th. The spots at the border becoming lines, and running 
towards the base of wings. 
