scientific works still less help is to be looked for; it also seems to point 
to the fact that the lines of evolution followed by the lepidopterous 
pupa have not only been unnoticed but, one might suppose, have hardly 
been regarded as existing. 
It follows from this, that the material on which this paper is based 
— viz., such butterfly pupge as I have myself been able to examine—is 
extremely meagre, not amounting to more than 2 or 3 per cent, of the 
ten thousand and odd species of butterflies that exist; again, while it 
has been abundant in some families, there are other families of which 
I remain entirely ignorant. The material at my disposal is, however, 
sufficient to bring out some important points very distinctly, but others 
are still obscure and untouched. It is necessary for me, therefore, to 
say emphatically at this point that where I make any statement broadly 
or dogmatically, I do so always with the proviso understood (but which 
it would be wearisome continually to repeat), that such statement is 
correct only so far as my observations have extended. 
To lay this paper before you with such a narrow basis for its 
foundation, may perhaps require an apology; if so, the apology would 
be, that valuable conclusions may be reached even from this narrow 
basis, and that the basis is not likely to be materially widened at any 
early date unless attention is called to the subject by some such paper 
as the present. 
I shall refer to various characters of the pupa? and, in support of 
the conclusions to which these appear to point, to a few matters out¬ 
side pupal structure: but I desire to direct attention chiefly to the 
progress which is evident in the pupse of the Rhopat ocera, as in those 
of Heterocera, from a condition of greater to one of less freedom of 
movement of the segments; to the progress from a greater number of 
exposed appendages (a decided “ Micro ” character) to a less number, 
though this is not illustrated amongst butterflies except, perhaps, as 
between Hesperids and Papilionids ; and to a general progress towards a 
smoothly rounded, solid form, which, however, is greatly interfered with 
amongst the butterflies by the exigencies of the development of pro¬ 
tective resemblances. 
I am not aware of any instance in which a pupa appears to have 
been derived from an ancestor which possessed a less number of 
movable parts and, provisionally, I take it, as a rule, that movement is 
NEVER REGAINED BY A PUPA WHEN IT HAS ONCE BEEN LOST. That this 
should be so, is by no means self-evident but, as a matter of observation, 
it appears to be the case. 
In the course of my study of pupae and of some other matters in 
connection with Lepidoptera, the conclusion has forced itself upon me, 
that a circumstance in the progress of evolution which I had believed 
to be rather rare is really very common. This is, that similar structural 
characters (sometimes one might almost say identity of structural 
characters) have been reached along different lines by descendants 
from a common ancestor, who did not present any indication of them. 
One of the most notable instances of this is to be found in the form 
of pupa which I have described (Trans. Ent. Soc. Lon., 1893, ji. 97) 
as characteristic of the Macro-Heterooera ; that is, a pupa in which 
the first four abdominal segments form part of the thoracic mass, the 
5th and 6th being free to move on their neighbours, whilst the 7th, 
8 th, 9th and 10th form another solid piece. One might look upon this 
