president’s address. 
I 57 
The last case of protective resemblance in Butterflies to 
which I shall allude is a very remarkable one. There is 
a large Butterfly belonging to the genus Caligo, which is 
restricted to the neotropical region, and which is found in 
central America and Brazil. The upper surface of this 
insect is of a dull slaty-blue colour, but the under surface 
bears a remarkable resemblance to the head of a large Owl. 
There are two large eye spots, each with a black pupil and 
yellowish iris, and the rest of the under surface is marked 
with lines and pencillings of sepia-brown on a greyish-white 
ground, producing a singular likeness to the plumage of an 
Owl. The cause for this colouration would seem to be that 
the great enemies of these Butterflies are Bats, which attack 
it when at rest at night ; but the great enemies of Bats are 
Owls, and the likeness of this insect by night to an Owl is 
so great that the Bats are afraid to meddle with it. 
Another very interesting problem in Natural History 
which is well illustrated by Butterflies is that of mimicry. 
By mimicry in its restricted sense is meant the superficial 
resemblances which exist between animals belonging to 
different species and often far removed from each other in 
the scale of classification. It does not include those re- 
semblances to surrounding objects to which I have already 
alluded under the name of protective or cryptic resemblances. 
Of true mimicry there are two forms, to account for which 
two hypotheses have been invented. In the first form the 
deceptive resemblance is borne by harmless and palatable 
species to those which are unpalatable or otherwise defended. 
These are known as cases of Batesian mimicry, as they were 
first described by Mr. Bates, the Amazonian traveller. 
The second form of mimicry exists between species which 
are specially defended, and these were explained by F. Muller, 
as due to the advantageous adoption of a common advertise- 
ment by which the loss of life occasioned by the education 
of young and inexperienced enemies is spread over a large 
