194 



NATURE 



[Dec. 27, 1 1 



pages, giving a charming and life-like account of the 

 White Mountains of New Hampshire and the butterflies 

 found there. This seems to be one of Mr. Scudder's most 

 happy hunting-grounds, and is the only known home, 

 with the exception of the Alps of Colorado, of CE. semidea, 

 the White Mountain butterfly, whose history comes next, 

 and takes up no less than sixteen pages. These include 

 the synonymy and references, which are full and appear 

 accurate ; two snatches of poetry (which, by the way, is 

 freely scattered throughout the work) ; a description of the 

 imago, covering two whole pages of close print ; others 

 of the ^gg, larva, and chrysalis, which take two more ; 

 geographical distribution occupies another page. The 

 remainder is devoted to life-history and habits, and ends 

 with a paragraph mentioning the desiderata left to be filled 

 up before our knowledge of the history of the insect is 

 complete. 



Not so satisfactory, in my opinion, is the history of 

 Cercyonis {Satyrus) alope and its near congener nephcle, 

 because, in the first place, not a word is said, in a generic, 

 description extending over three pages, to show how this 

 genus difters (if it does differ) from the genus Satyrus or 

 HipparcJiia^ in which the American species are included 

 by other authorities ; and, secondly, nothing is said as to 

 whether this generic description is based on the two forms 

 which alone are found in New England, or on the 

 characters of other North American species ; which, 

 indeed, are not even named, though their existence is 

 alluded to. As an instance of the difficulty of getting 

 any agreement as to what constitutes a species among 

 butterflies, even when they have been bred as largely, 

 and studied as closely, as this species has been by W. H. 

 Edwards, I may quote Mr. Scudder's remarks : — 



" It has been generally conceded of late years that these 

 two types of butterflies were only dimorphic forms of a 

 single species ; and I have myself shared in this view, 

 which has been supposed proven by breeding experiments 

 and direct comparisons of a large amount of material 

 made by Edwards, who, far more than all other observers 

 together, has increased our knowledge of the natural 

 history of these butterflies. 



" He has instituted comparisons between them at every 

 stage of life ; and while he sees differences between cater- 

 pillars and chrysalids born of differe«t types, he finds 

 no constant and universal distinctions ; while as to the 

 relation of the early stages of the butterflies, he has 

 proved by breeding that 'south of the belt of di- 

 morphism,' as he calls that strip of country where 

 C. alope and C. 7jephele both occur, ^ alope produced 

 alope,' but inside the belt, alope produced intergrades, 

 and iiepJicle produced alope and also an intergrade. . . . 

 That nephele, north of the belt, breeds true, is certain, 

 because the intergrades and alope are not found here. 



"This would be conclusive if the complete parentage 

 in each case were known ; but, as only the mother was 

 known in any case, another explanation is not only pos- 

 sible, but in view of all the facts probable. The inter- 

 grades found throughout the belt forming the northern 

 boundary of the typical alope, and the southern boundary 

 of the typical nepkele, seem to be far more easily explain- 

 able on the hypothesis of hybridism, since they occur 

 only where such a phenomenon is possible, and wherever 

 it is possible. The same argument applied to the case of 

 Basilarchia, as has been done by Edwards, would logically 

 prove more than he would agree to, viz. the specific 

 identity and trimorphism of all the eastern species except 

 Basilarchia archippics. That the species of Cercyonis 

 here described are certainly distinct, I would by no 



means maintain ; only that, in view of the facts of dis- 

 tribution, it seems more probable that they should be 

 looked upon as having reached in their development 

 the stage of specific distinction, whilst they are readily 

 fertile inter se, and produce intergrades, where they meet 

 on common ground." 



It seems to me, however, that there is yet another ex- 

 planation, which, from what we know of the effect of heat 

 and damp on the variation of butterflies of the same family 

 in India, is even more probable ; and that is, that the 

 species is one which, having a wide range of distribution, 

 is affected in the southern part of this range by climatic 

 conditions which do not exist in its northern habitat, 

 and has become modified in consequence, whilst in the 

 central part of its range, the climatic conditions being 

 more variable, the insect is also itself more variable. 

 The most ardent devotee of minute subdivision of species 

 cannot fail to allow, after Mr. de Nicdville's experiments 

 on breeding in Calcutta, that climate can and does pro- 

 duce in the same locality, at different seasons, changes 

 which are far greater than the difference which exists 

 between alope and nepkele, a difference which can be 

 matched in other species of SatyridjE, about the specific 

 identity of which there has hitherto been little or no 

 question. 



It does not seem to me logical for Mr. Scudder to treat 

 of these two forms as different species, when he allows 

 the specific identity of such forms as Cyafiiris {Lyccena) 

 pseiidargiolus, hicia, violacea, and neglecta ; this view 

 being based, as it must be, on similar breeding experi- 

 ments, carried out by the same naturalist, who proved to 

 his own satisfaction and to mine the identity of alope and 

 nepkele. 



A marked and novel feature of this work, which I 

 cannot too highly praise, is the separated map of 

 geographical distribution given on Plate 18 for most 

 of the species dealt with in this part. Cn a small chart 

 of the United States and Canada, the range of each 

 species is coloured in brown, so that one can see at a 

 glance what the distribution is ; and though, no doubt, in 

 the less known parts of the country these maps are not 

 strictly exact, yet they give a very fair idea of what would 

 otherwise require much reading to understand. 



I look forward with the greatest interest to the succeed- 

 ing parts, and to the early completion of, this most valu- 

 able work, which will take a high place among biological 

 monographs, and will rank like Edwards's " Butterflies of 

 North America," as one of the most important, beautiful, 

 and painstaking books which America has ever produced 



H. J. Elwes. 



POLE'S LIFE OF SIEMENS. 

 Tke Life of Sir William Siemefis, F.R.S. D.C.L., LL.D. 

 By WiUiam Pole, F.R.S. (London: John Murray, 

 1888.) 



IS it perhaps to the spirit of this book-making age that 

 we ought to attribute the fact that examples of un- 

 satisfactory biographies have been frequent in recent 

 years ? Perhaps works of this kind are too hurriedly 

 compiled, and are laid before the friends and the public 

 at a date too early to allow of such a memorial proving 

 really satisfactory to the one class or to the other. 



