164 THE INSECT WORLD. 



arranged like the bands round the heads of mummies ; the back 

 is plain and rounded in a great number of pupae. 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 pupaB 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 cavi- 

 ties may represent the eyes (Fig. 125). 



The colours of angular pupae attract our attention. 

 ^ ome are superbly covered ; they appear 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. 

 Reaumur 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 light 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, 

 Reaumur 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 pupae 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 %pv(rog, 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. ED. 



