234 THE ENTOMOLOGIST. 



it flourished better than now, when protected. If as rare, 

 how could it have survived at all before and during its trans- 

 mutation ? It would, perhaps, be suggested that the Lep- 

 talis was formerly commoner than now, and that some 

 enemy arose, rendering it necessary that the Leptalis 

 should find a new means of defence. This, however, was 

 mere supposition, and it was almost impossible to adduce 

 facts to prove it ; but supposing it to be the case, why did 

 not the enemy exterminate the Leptalis when it did not 

 resemble the Heliconia, as (according to the theory) it would 

 now, but for this resemblance. The further supposition must 

 be made, that the enemy was not at first very dangerous to 

 the Leptalis, and that in proportion as it grew dangerous the 

 Leptalis grew more and more to resemble the Heliconia : it 

 was certainly very fortunate for the Leptalis that spontaneous 

 variations, bringing it to resemble the Heliconia, should 

 occur in the exact proportion required for its safety. 



6th. Again, taking the time when the Leptalis differed in 

 pattern from the Heliconia, it was said, that specimens ex- 

 hibiting small variations approximating to the Heliconia 

 were selected for the preservation of the species. But a small 

 variation in marking would be of no practical service to the 

 Leptalis, especially as it was by its nasty odour that the He- 

 liconia was protected ; to which it might be added that on 

 the theory of Natural Selection no reason or fact was brought 

 forward to induce the belief that variations of the required 

 sort should occur at all. 



In conclusion, Dr. Sharp expressed a very decided opinion 

 that the evidence as yet adduced was insufficient to convince 

 an unprejudiced observer of the truth of the theory of mi- 

 metic resemblances. The theory was very ingenious, and 

 might or might not be true. 



Mr. Wallace replied at great length, reviewing Dr. Sharp's 

 six propositions with great care and fairness, but adducing 

 no arguments differing from those with which Entomologists 

 are already familiar as employed by the advocates of the 

 theory. 



Mr. Westwood then reiterated the opinions he has pre- 

 viously expressed, and the President closed the discussion. 



