164 ; THE INSECT WORLD. 
arranged like the bands round the heads of mummies; the back 
is plain and rounded in a great number of pup. But a great 
many others have on the upper part, along the edges which 
separate the two sides, little humps, eminences broader than they 
are thick, ending in a sharp point (Fig. 125). 
The head of the angular pups terminates sometimes in two 
angular parts, which diverge from each other like two horns 
(Fig. 126). In some other cases they are curved 
into the form of a crescent. These appendages some- 
times give to the pupa the appearance of a mask, 
especially as an eminence placed on the middle of 
the back is rather like a nose, and the small cavyi- 
ties may represent the eyes (Fig. 125). 
The colours of angular pupe attract our attention. 
ee Some are superbly covered; they appeared to be 
Butterfly. wrapped in silk and gold. Others have only spots of 
gold and silver on their belly or their back. All, however, have 
not this remarkable splendour, nor these metallic spots. Some are 
green, yellow, and spotted with gold. Generally, they are brown. 
Réaumur has shown that this golden colour is not due, as was 
thought for a long while, to colouring matter, but to a little whitish 
membrane, placed under the skin, which reflects the ight through 
the thin outer pellicle, in such a manner as to produce the optical 
illusion which imparts to the robe of the chrysalis the golden hues 
of a princess in grand costume. All is not gold that glitters, 
Réaumur proves literally, in the case of chrysalides.* 
Let us add that the chrysalis remains thus superbly dressed as 
long as it is tenanted, but loses its colour as soon as the butterfly 
has quitted it. 
The cone-shaped pupz belong to the twilight and night-flying 
Lepidoptera, and to those butterflies whose caterpillars are onisci- 
form, or in shape resembling a wood-louse. ‘They are generally 
oval, rounded at the head, and more or less conical at the lower 
end. Their colour is generally. of an uniform chestnut brown. 
What a mystery is that accomplished in the transition from the 


* The word is derived from ypvooc, golden; for that reason pupa is a better word 
than chrysalis, as this only strictly applies to a very small number; for the same 
reason aurelia is a bad word.—Ep. 
