1896.] ON THE OBLIQUE SEPTA IN’ THE PASSERINES. 225 
with which this takes place seems wonderful and to me somewhat 
analogous to crystallization in inorganic matter. If the elytra are 
examined from their upper surface, the difference between the 
larger punctures surrounding the spots and those of the ground- 
colour is very marked, the latter being irregularly and the others 
regularly placed ; but if the elytra are removed and examined from 
the inner side, a thin layer of skin covers the entire surface, but 
the punctures shine through it and seem of nearly equal size and 
much more numerous. I may further mention, that all the spots 
or bands on the upper surface seem slightly convex and show 
rarely any punctures except round their margins. These are all 
the observations I am able to record; and I must leave to anatomists 
to form any conclusions, if such are possible, as to the way in 
which nature has worked here, and whether we could obtain any 
clue by examining the insect in its native place, when immature 
and in process of formation, so as to get some idea how colour, so 
distinct from punctuation, can influence the latter or the reverse, 
when this is apparently the case in so exceptional an instance as 
the present. The subject itself is not new, having been noticed 
by Chapuis and myself some years ago, but I think it well to draw 
attention to it again, so that more observations may be made, if 
possible. 
4, On the Oblique Septa (“‘ Diaphragm” of Owen) in the 
Passerines and in some other Birds. By Frank E. 
Bepparp, M.A., F.R.S., Prosector to the Society, 
Examiner in Zoology and Comparative Anatomy to the 
University of London. 
[Received December 16, 1895.] 
The facts which I bring before the Society have been accumu- 
lating in my notebook for the last few years, and even now there 
are numbers of types of Passerine birds which I have not had, and 
may never have, the opportunity of examining. Less emphasis, 
therefore, must be laid upon such classificatory conclusions as 
I venture to bring forward, than upon the actual facts which I 
record. There are a certain number of desirable Passerine genera 
represented in the rich spirit stores of the Prosector’s department, 
but not referred to in the present paper; I have thought it unwise 
to make any use of them, since fresh material is so essential for the 
proper study of delicate and transparent membranes. 
The greater part of the present communication deals with the 
divergent structure of what Prof. Huxley’ has termed the “ oblique 
septum” in Passerine birds. I may therefore conveniently 
commence with a description of the normal arrangement of 
this structure, as it is seen for example in the Duck. And I 
avail myself of Prof. Huxley’s own words?:—“ The second so- 
: 1 “ On the Respiratory Organs of Apterya,” P. Z. 8. 1882. 
on 2 Loe. cit. p. 561 
Proc. Zoo. Soc.—1896, No. XV. 15 
