The Zoologist — April, 1871. 2565 



oceanic islands with the smaller forms of animal life ; though, no doubt, 

 floating timber had the same effect, but in a lesser degree. 



Mr. Bates and Mr. Pascoe asked how it was that the Coleopterous fauna 

 of the opposite sides of high mountains, and mountain-chains, presented 

 such marked differences, if their insect-inhabitants were liable to be carried 

 over the summits by atmospheric agencies? And Mr. F. Smith, Mr. 

 Pascoe, and Mr. M'Lachlan remarked on the extreme difficulty of natu- 

 ralising insects in localities which apparently present no important 

 climatic differences from those in which the species experimented upon 

 are abundant. 



Mr. Miiller, agreeing with the suggestion thrown out by several members, 

 explained this by the hypothesis, that though many individuals are dispersed 

 in the manner he indicated, yet, owing to causes difficult to comprehend, 

 the strangers are unable to cope with the pre-existing denizens of the 

 locality, and thus only very few are able to maintain their position, and 

 most of these die out before they are able to give birth to new varieties or 

 incipient species. 



Mr, Bates said that this explanation quite accorded with his own views 

 on the subject. 



Mr. Smith enquired the exact meaning attached to the terms " migratory" 

 and " non-migratory," as applied to insects, m connection with Mr. Miiller's 

 paper. 



Mr. Stainton suggested that in the one case the insects might be 

 considered fi'ee agents, whereas, in the other, compulsion was necessary to 

 force them from their customary habitats. But it was remarked that the 

 terms were ill chosen, inasmuch as migration, in the sense in which the 

 term is applied to birds, does not exist with insects, much of the so-called 

 migi'ation of these being dependent upon the supply of food being insufficient 

 to satisfy the wants of vast hordes of a particular species ; this, in some 

 cases, as in the locusts, being the normal condition, rendering them habitual 

 wanderers, whereas, in others, it was of only occasional occurrence. 



Mr. H. Jenuer-Fust communicated a supplement to his paper " On the 

 Distribution of Lepidoptera in Great Britain and Ireland." 



New Part of ' Transactions.' 

 Part 5 of the ' Transactions' for 1870 was on the table. 



March 6, 1871. — A. R. Wallace, Esq., President, in the chair. 



Donations to the Library. 



The following donations were announced, and thanks voted to the 



donoi-s : — ' Proceedings of the Royal Society,' No. 125 ; presented by the 



SECOND SERIES — VOL, VI. X 



