Bibliographical Notice. 333 



is whether it be a paler, greyer form of costirufaria, with 

 which it agrees in structure, unless perhaps the fore wing be 

 slightly more pointed ; in both, the wings are distinctly 

 elongate, the termen of the fore wing long. 



[To be continued.] 



BIBLIOGRAPHICAL NOTICE. 

 The Biology of Birds. 



A History of Birds. By W. P. Ptceaft, Zoological Department, 

 British Museum. With an Introduction by Sir Bay Lankestek, 

 K.C.B., F.R.S. Pp. xxx + 458. With 38 Plates and numerous 

 Figures. Methuon & Co., London, 1910. Price 10s. Qd. 



Among the many books on birds this new one by Mr. Py craft 

 occupies a distinctive place. It is, we believe, quite by itself — a 

 Biology of birds, permeated through and through with the Evolution- 

 idea. For just as the theologian sees everything sub specie ceterni- 

 tatis, so the post-Darwinian biologist sees everything sub specie 

 evolutionis. So many zoological books have encouraged our hopes 

 in their prefaces by declaring their intention to give prominence to 

 habits and history, and have soon dashed them to the ground by 

 adopting a thoroughly statical mode of treatment, that we almost 

 expected that Mr. Py craft would likewise fall victim to his specialisms, 

 and give us a beautiful treatise on comparative osteology with the 

 bird as a natural climax. We hope that he will do this by and by, 

 for he has a rare osteological insight ; but we are glad that he has 

 kept true to his biological programme, and worked it out with so 

 much success. There was need for a book of this kind, and we 

 have now a posteriori as well as a priori reasons for knowing that 

 Mr. Pycraft was the man to write it. 



Let us first indicate the scope and arrangement of the book. 

 The introductory chapter discusses the structure and internal 

 functions of birds, the second their pedigree, the third their classifi- 

 cation, or,rather, the linesof their evolution. Then follow chapters on 

 geographical distribution, the seasonal punctuation of the bird's life, 

 and migration. Inter-relations between birds and other organisms, 

 between birds of different kinds, and between the members of a bird- 

 community form the subject of a natural group of three chapters. 

 The author then passes to the relations of the sexes, the nest, the 

 eggs, the care of the young, the adaptations of nestlings — another 

 fine series. A chapter on development and life-history, considered 

 in their broad oecological aspects, leads on to variations, modifica- 

 tions, natural selection, sexual selection, and isolation — a series 

 that makes in itself a vivid introduction to the study of evolution. 

 Having discussed the raw materials of evolution and the directive 

 factors, Mr. Pycraft returns to the results achieved — the adapta- 

 tions, both static and dynamic, that are so conspicuous in a highly 

 evolved class such as birds. The volume concludes with a chapter on 



