1865.] Entomology. 461 



V. ENTOMOLOGY. 



(Including the Proceedings of the Entomological Society.) 



A most important contribution to Natural History as well as to Ento- 

 mology has just been published by the Linnean Society. It is an 

 article by Mr. A. K. Wallace, " On the Phenomena of Variation and 

 Geographical Distribution, as illustrated by the Papilionida} of the 

 Malayan Region." It is of course written from the Darwinian point 

 of view, but is especially valuable as embodying the observations made 

 by the author on that particular family of butterflies during his long 

 and arduous explorations in the Eastern Isles. We can only give a 

 brief abstract of a paper which occupies nearly 71 quarto pages, and 

 regret that our space will not permit a more detailed analysis. 



The greater sensibility of the diurnal Lepidoptera to modifying 

 causes is well known, and therefore in no other families of insects 

 is there so much difficulty in determining what are species and what 

 only varieties. The definition of Pritchard, that " separate origin and 

 distinctness of race, evinced by a constant transmission of some cha- 

 racteristic peculiarity of organization," constitutes a species, is 

 adopted by Mr. Wallace, so far as when the difference is not confined 

 to a single peculiarity, and leaving out the question of origin. To this 

 it may be objected that practically it will be all but impossible to tell 

 what peculiarities are constant, or transmitted from generation to 

 generation, in the great mass of specimens that may come under the 

 eye of the Entomologist. Besides, 1st, simple variability, Mr. Wallace 

 distinguishes — 2nd, polymorphism (or dimorphism) ; 3rd, local forms ; 

 4th, coexisting varieties ; 5th, races or subspecies ; and 6th, true species. 

 By simple variability the author includes " all these cases in which the 

 specific form is to some extent unstable." Closely allied to some of 

 these variable species are others, which, though only slightly differing 

 from them, are constant and confined to limited areas. These local 

 forms are treated by Mr. Wallace as distinct species. Polymorphism 

 or dimorphism implies the coexistence of two or more distinct forms 

 in the same locality, " occasionally produced from common parents," 

 the union of these distinct forms not producing intermediate varieties, 

 but reproducing the parent forms unchanged. Several curious cases 

 (generally confined to the female sex) are given, but the phenomena 

 will be more clearly understood by the following illustration : — Sup- 

 pose " a blue-eyed, flaxen -haired Saxon man had two wives, one a 

 black-haired, red-skinned Indian squaw, the other a woolly-headed, 

 sooty-skinned negress, — and that instead of the children being mu- 

 . lattoes of brown or dusky tints, mingling the separate characteristics 

 of their parents in varying degrees, all the boys should be pure Saxon 

 boys like their father, while the girls should altogether resemble their 

 mothers. This would be thought a sufficiently wonderful fact ; yet 

 the phenomena here brought forward as existing in the insect world 

 are still more extraordinary ; for each mother is capable not only of 

 producing male offspring like the father, and female like herself, but 

 also of producing other females exactly like her fellow- wife, and alto- 



