93 
real antennæ —), combined with the outturned lobe of the hind-edge 
of the wing, bear witness enough that this is a very specialized 
Structure, not a simple rudiment of a formerly larger wing. 
It should still be mentioned that I had the opportunity of ob- 
serving also another species of Thecla, occurring in our country, 
Th. quercus (Fig. 19). It did not move its hindwings any more 
than Th. W- album, and the shape and design of the hindwing 
give still less impression of a head than is the case in W- album. 
This species would then represent a still more reduced — or per- 
haps more primitive — stage than W- album. It may, however, 
be stated that it was a cold and rainy day I observed it — per- 
haps it may behave otherwise in warm, sunny weather. 
Also another butterfly, Gynæcia dirce Linn., appears to have a 
similar adaptation, though much less perfect than in the Thecla's (PI. I, 
Fig. 10). This' butterfly usually rests on tree trunks, with the wings 
closed, and always head downwards. When in this position, the short 
end lobe of the hindwings very much resembles a head — and, as 
Seen in the figure, also in this case there are lines in the markings 
of the hindwings, which converge towards the false head, and also 
the color is somewhat brighter towards the lobe. The wings do not 
Move up and down, and there is nothing to indicate antennæ. 
Upon the whole this is a much less elaborate disguise than what 
is found in the Thecla's. Still, on observing the butterfly resting 
in its natural position on the tree trunks one cannot resist the 
impression that it is the head turned upwards, and that the mean- 
ing of it must be, that lizards are thereby induced to direct their 
attack at this non-vital point, the butterfly thus escaping. — The 
Same objections, of course, apply to this case as to the Thecla's: 
Il have never seen an injured specimen (— but I have hardly 
Seen more than a dozen specimens -—) and, in case it does work 
after its Supposed meaning, it can do so only once. 
Although this peculiar device of simulating a head in the wrong 
end is specially developed in the Lycænids, it is not entirely unknown 
in other animal groups. Shelford in his book ,,A Naturalist in Bor- 
neo" describes (p. 230) a larva of a Noctuid, in which the posterior 
end looks startling like an ant. ,, Nearly all the segments of the body 
are furnished with fragile tentacle-like processes. The anal prolegs 
are large, and can be completely divaricated; just above each is 
