518 TRANSACTIONS OF SECTION D. 
In the case of Planema epea paragea the model is more abundant than the 
mimic—due to the fact that I found a particularly good place for catching them 
when they were collected together. Generally they were very scarce. 
In a very large collection of these same forms made by Mr. C. A. Wiggins at 
Entebbe, on the mainland twenty-five miles north-east of Bugalla, models are 
very abundant, as well as the mimics. The mimics, however, vary hardly at all. 
The suggested explanation is that on the mainland the models are sufficiently 
numerous for resemblance to them to have a definite selection value to the mimic, 
so that natural selection keeps them true to the type of the model. 
On the island models are too scarce for it to be of any value to a mimic to 
resemble them; so that varieties persist which on the mainland are at a dis- 
advantage, and are quickly destroyed by enemies. Stronger proof of the reality 
of mimicry and of the power of natural selection to maintain the mimetic 
likeness could hardly be desired. 
6. The Geographical Relations of Mimicry. By Dr. F. A. Dixsy, F.B.S. 
It is well known that certain definite schemes of colour and pattern in the 
wings of butterflies are characteristic of certain definite geographical regions. 
This is true not only of the region as a whole, but also, in many cases, of the 
smaller districts into which the given region may be divided, the colour and 
pattern undergoing a similar modification in all the members of the associated 
assemblage as one such district gives place to another. 
Illustrations of this phenomenon are afforded by a well-known combination of 
red, black, and yellow Ithomiine, Heliconiine, Danaine, Nymphaline, and Pierine 
butterflies in Central and South America, and by a similar parallelism existing 
between local forms of the African genera Mylothris and Phrissura. The con- 
stituent members of these assemblages are often of very diverse affinities. 
It is natural to seek for an explanation of these facts in the direction of a 
common influence exercised by the geographical environment. But in the special 
cases cited, to which many others might be added, this explanation is attended 
by such extreme difficulty as to be practically put out of court. The inter- 
pretation that at present holds the field is that which attributes these 
resemblances, with their correlated geographical modifications, to the action 
of mimicry, whether of the Batesian or Millerian kind. This interpretation 
rationalises the geographical facts without resorting to the exceedingly difficult 
hypothesis of a direct influence by the geographical conditions. 
If the interpretation under the theories of mimicry be accepted there still 
remain some anomalies to be accounted for. A few of these may be set down as 
mere coincidences, such as might be expected where the array of facts is so 
extensive; others are probably due to migration on the part of the insects them- 
selves or of their enemies; while there is a residuum which no doubt points to 
the fact that somewhat similar schemes of colour and pattern may take indepen- 
dent origin in entirely distinct regions of the earth’s surface, and may in each 
such situation become the common property of a Batesian or Miillerian mimetic 
assemblage. 
7. Discussion on Mimicry. 
(i) Mimicry. By Professor E. B. Pounron, F.R.S. 
Special attention was drawn to the relationship between birds and butter- 
flies and to the examples of injuries actually seen to be inflicted by wild birds, 
and, in comparison, examples of injuries very commonly found in butterflies. 
Stress is to be laid on ‘disabling injuries,’ such as the loss of the whole of a 
wing, indicating that the insect had not escaped, but was abandoned after 
being mutilated. There is evidence to show that these injuries are especially 
characteristic of the great groups which supply the models for mimicry. The 
author pointed to the negative evidence derived from the examination of birds’ 
stomachs, and exhibited pellets thrown up by birds after a meal of butterflies, 
showing how completely the nature of the food has been disguised. The author 
