2Q [January, 



Tlie centenary year of the birth of Cliarles Darwin has in due course 

 produced a hirge number of important memoirs bearing iipon the life and work 

 of the author of tlio " Origin of Species," and Professor Poulton's very valuable 

 contribution to the Darwinian literatiire of 1909 appears liappily and most 

 appropriately on the fiftieth anniversary of the publication of that epoch- 

 making work. As one of the chief modern exponents of the theory of Natural 

 Selection, the learned Professor has taken a leading- part in the celebrations in 

 honour of the great Naturalist, whom all Entomologists may well claun as one of 

 themselves. The addresses delivei-ed by liim on these occasions to represen- 

 tative gatherings of scientific men at home and in America, are brought to- 

 gether in a very convenient and attractive form in this volvune, which is 

 appropriately dedicated to Darwin's now venerable feliow-woi-ker Dr. A. R. 

 Wallace. The first two addresses, which were delivei-ed on the opening day of 

 the centenary year before the American Association for the Advancement of 

 Science at Boston, are devoted to a masterly resume of the history and progTess 

 of the theory of Evolution during the half-century which has elapsed since the 

 appearance of the " Origin," and to the influence of Darwin's commanding 

 intellect and character in helping to achieve the vast transformation of scientific 

 thought during that interval of time. Section V is reproduced from the Cam- 

 bridge Centenary volume "Darwin and Modern Science " and is entitled " The 

 Value of Colour in tlie Struggle for Life." Here we liave Professor Poulton 

 at his best, in dealing with a subject whicli appeals specially to Entomologists, 

 and one that he has made liis own. In this most interesting essay due weight 

 is given to the observations of the great naturalist-traveller W. J. Burchell — 

 a worthy predecessor of Charles Darwin — on the cryptic and mimetic resem- 

 blances of insects and plants in South Africa and Brazil : and it is noteworthy 

 that Burchell was present at the historic meeting of the Linnean Society on 

 July 1st, 1858, when the Darwin-Wallace essay was read. " Mimicry in North 

 Americaia Butterflies," which forms the subject of the next section, is of even 

 more direct interest to Entomologists as indicating an exceedingly fruitful 

 line of research, and will be new to many of them, though it has been in part 

 anticipated by the author's memoir in Trans. Ent. Soc. Lond., 1908, pp. 447-488. 

 Dannida (Anosia) ;plexippus is here shown on convincing evidence to have been 

 originally a native of tropical Asia, where its nearest allies still exist ; and the 

 accoxmt of the effects of its comparatively recent invasion of the American 

 Continent on the indigenous forms of Limenitis, resulting in the case of 

 L. archippus in one of tlie most jjerfect examijles of mimicry known, adds still 

 further interest to the history of perhaps the most remarkable of all butterflies. 

 An almost equally striking case, here set forth in detail, is that of the influence 

 of Pharmacophagus {Papilio) philenor, probably an intruder into North America 

 from the South, on members of the plastic genus Limenitis as well as on other 

 Papilionidoe with which it has come in contact. The final section, which many 

 will think justifies in itself the ajDpearance of the book, embodies a series of 

 nineteen letters, hitherto unpublished, from Charles Darwin to the veteran 

 Entomologist Mr. Roland Trimen, between the years 186."^ and 1871 ; and these, 

 with another letter to the Rev. P. W. Hope of date 1837 (pp. 202-.S), published 

 for the first time in Section V, are a most valuable and characteristic addition 

 to the correspondence of our great Natui'alist as given to the Avorld. — J. J. W. 



