94 
a prominent black spot. When the larva is irritated, the posterior 
part of the body is immediately reared up, the anal prolegs are 
thrown widely apart, and the more posterior tentacles are violently 
agitated. When the larva is seen end-on it looks very like an ant, 
the eye-spots like ant's eyes, the tentacles like the legs, while the 
antennæ are represented by the last pair of tentacles which are 
elbowed like these organs in an ant.” Also a small spider, Amyciæa 
lineatipes, mimics the Keringa ant, in whose nests it lives, in the 
curious way that ,the head part of the ant is mimicked by the 
abdomen of the spider, which near its apex bears two black spots 
like the eyes of an ant". 
Also among Vertebrates this character occurs at least in one 
instance, viz. the little fish, Chætodon plebejus, mentioned above, 
(p. 60). But possibly there are some other cases. According to 
Hagen") the poisonous snake Elaps furcatus Schneider of Su- 
matra has the habit, when alarmed, to raise head and tail and 
then roll up the tail end in a spiral, whereby it looks like a widely 
opened mouth; the matives are naming it the two-headed snake. 
Further Mr. H. Winge has kindly called my attention to the 
Australian short-tailed Lizard, Trachysaurus rugosus Gray., the 
short and rounded tail of which corresponds so closely in its out- 
line and proportions with the head, that it was originally described 
by its 'discoverer, Captain W.Dampier, as a double-headed animal. 
»It had no tail, and at the rump, instead of a tail there, it had a 
stump of a tail which appeared like another head, but not really, 
such being without mouth or eyes; yet this creature seemed by 
this means to have a head at each end."”) What further adds to 
this likeness of the tail end to a head is, as Mr. Winge pointed 
out to me, the fact that the hindlegs are almost exactly like the 
forelegs in shape and length. 
Whether this feature is really of any protective value to the 
animal, in the same way as the false head of the Thecla's, can, 
of course, only be decided by observations of the animal in its 
natural surroundings. I am not aware, that such observations have 
been made. 
") Quoted from Piepers. Mimicry, Selektion, Darwinismus. 1903. p. 213. 
”) Quoted from ,,Living animals of the world", p. 578— 
