326 Darwin, and after Darwin. 
tective Resemblance, and one may search a long time before 
finding it, although assured of its presence from the stripped 
branches of the food-plant and the faces on the ground beneath. 
As soon as a large larva is discovered and disturbed it with- 
draws its head into the first body-ring, inflating the margin, 
which is of a bright red colour. There are two intensely black 
spots on this margin in the 
appropriate position for eyes, 
and the whole appearance is 
that of a large flat face ex- 
tending to the outer edge of 
the red margin (see Fig. 112). 
The effect is an intensely ex- 
azgerated caricature of a ver- 
tebrate face, which is probably 
alarming to the vertebrate 
Fie. 112.—The larva of Puss Moth enemies of the caterpillar. The 
in its terrifying attitude after be- Lise 3 
ing disturbed; full-fed; natural terrifying effect is therefore 
ee. mimetic. The movements en- 
tirely depend on tactile im- 
pressions: when touched ever so lightly a healthy larva im- 
mediately assumes the terrifying attitude, and turns so as to 
present its full face towards the enemy; if touched on the 
other side or on the back it instantly turns its face in the ap- 
propriate direction. The effect is also greatly strengthened by 
two pink whips which are swiftly protruded fiom the prongs 
of the fork in which the body terminates. The prongs represent 
the last pair of larval legs which have been greatly modified 
from their ordinary shape and use. The end of the body is at 
the same time curved forward over the back (generally much 
further than in Fig. 112), so that the pink filaments are brandished 
above the head. 
Mimicry. 
Lastly, these facts as to imitative and conspicuous 
colouring lead on to the yet more remarkable facts of 
what is called mimicry. By mimicry is meant the 
imitation in form and colour of one species by another, 
