616 Dr. G. D. Hale Carpenter on 
Now on the island it is quite conceivable that an enemy 
of the Pseudacraeas might never see a Planema at all: at 
any rate the latter are so extremely scarce that they can 
have little protective value, and the Pseudacraeas would 
gain little by resembling models that are much less common 
than themselves. Consequently any form of Pseudacraea 
that is produced will have as much chance of surviving as 
the most perfect mimic, and the transitional forms appear 
almost as abundantly as the types. On the mainland, 
however, conditions are very different. Owing to the 
abundance of Planemas, their presence is of definite pro- 
tective value to the Pseudacraeas, and varieties that are 
produced which do not conform rigidly to the types of the 
models are put at a disadvantage in the struggle for exist- 
ence, and are destroyed by enemies in preference to the 
types. On the mainland the mimics are kept rigidly up 
to the mark, and transitional varieties between hobleyz, 
turikensis and terra are by comparison rarely to be found. 
It may perhaps be argued that there is some condition 
productive of greater variability on the island, but not on 
the mainland. But though intermediate varieties are 
scarce on the mainland, yet they do occur, and it 1s difficult 
not to believe that they are rarely caught by collectors 
because they are so much more destroyed by enemies than 
are those which more closely resemble the models. If, as 
I believe, this explanation be the correct one, it supplies 
the strongest possible proof of the reality of mimicry and 
of the power of natural selection to preserve it—indeed it 
is a crucial test. 
LOCALITIES REFERRED TO IN THE FOLLOWING TABLES. 
Bugalla is a large island made up of broad northern and 
southern portions connected by an intermediate and com- 
paratively narrow section. A narrow arm runs eastward 
from the northern part, Buninga, and meets at a night 
angle a less narrow northward extension from the southern 
part. At the angle of Kerinya, as this isthmus is called, 
and near its N.E. shore, my camp was situated on a forest- 
ringed grassy hill about 150 ft. above lake level. The 
place is known as Lutoboka or Fort Stanley. Kerinya 
itself 1s bordered right down to the shore with forest, 
behind which grassy downs rise to a height of about 350 ft. 
The forest belt is in some places very narrow, not more 
