312 PROCEEDINGS OF THE ACADEMY OF (June, 
Suppose a different experiment were performed: let some muskrats 
(Fiber) be put into an aquarium with some sea-lions; would their 
efforts to escape indicate previous experience in evading enemies of 
the same class? Not at all, it would indicate merely adaptation to 
expert progression in the same medium. The relations of birds 
(in general) to bats and of birds (again in general) to dragonflies are 
instances illustrating the same fact, but which are due to no general 
predatory relation between the groups. The wonderful powers of 
flight of many of the Syrphide are strictly comparable to that of 
butterflies, as the adults feed only at flowers and have no need of 
expert flight for predatory purposes; also they do not need it so 
highly developed for defense, for rather a small proportion of birds 
are capable of catching insects so expert on the wing. The extreme 
rapidity and dexterity of flight of humming-birds has no possible 
relation to their prey, nor need it have been developed to its present 
perfection to evade species that might be inclined to prey upon 
hummers. When Mr. Pocock arrives at the true reason for the 
extraordinary powers of flight of humming-birds, he will undoubtedly 
be less insistent upon the predator-evasion theory as an explanation 
of the tortuous flight of butterflies.* 
Pocock further says: ‘‘Those who hold on the negative evidence 
above stated, that birds are not to be reckoned as serious enemies 
of butterflies, must be called upon to supply some explanation other 
than that above proposed of the marked reactions between these 
two classes of animals when brought into contact with one another, 
and to show reason why what takes place in the aviary may not be 
regarded as indicative of similar occurrences in nature” (p. 812). 
The pertinent retort to this statement is that it is the selectionists 
who first claimed and who still claim that birds are important enemies 
of butterflies, and it is up to them to produce real evidence in favor 
of their contention. So far they have brought forward little except 
results of experiments. Pocock’s own results, namely, the consump- 
tion of large numbers of British insects by exotic animals, should 
have convinced him that what takes place in the aviary may not 
necessarily be regarded as indicative of similar occurrences in nature. 
The point may be further illustrated by the following. Suppose a 
8 It is a matter of common observation that butterflies constantly exercise 
their powers of flight by playing with other butterflies even of different species. 
They often dart at falling leaves, flying bits of paper, and even birds. The 
writer saw (March 27, 1912, Plummer’s Id., Md.) a Vanessa antiopa dash at 
and come within a few inches of a phoebe (Sayornis), that had just perched after 
one of its customary quick sallies at insect prey. The bird, a highly insectiv- 
,orous species, paid no attention to the butterfly. : 
