46 Reviews. [,,f7„,y 



information concerning the Antarctic species of Petrels in the 

 ' Supplement ' to his ' Birds of New Zealand.' This Monograph, 

 however, is chiefly based on the large series of specimens in the 

 British Museum,' which now includes the original ' Salvin- 

 Godman ' collection." — A.J.C. 



[" Geographical Variations in Birds." By C. W. Beebe, Curator of Birds, The 

 Zoological Park, New York.] 



Some forty interesting pages are devoted to the subject, with 

 special reference to dichromatism and melanism in birds, as well 

 as in other animals. The moist parts of south-west and south-east 

 Australia are specially interesting in comparison, while Tasmania 

 fits in with " a decrease in size southward, in addition to a 

 change in colouration," for everywhere one sees the tiger snake 

 {HoplocepJialus atrtus) well showing the darkening tendency. A 

 second example always before us is the PacJiycepJiela vtelanura. 

 In Tasmania the black tail is constant, almost without exception, 

 while on the mainland one occasionally sees the black tail in the 

 mainland form {P. g?itturalis) of the island species. I take it 

 the Tasmanian form shows a clear case of melanism when the 

 grey tail is no longer grey but black. Reversion with change 

 from island to mainland may occur as with Mr. Beebe's examples 

 of south to north on the continent. In a case of melanism it is all 

 over the world, apparently, a difficult matter to fix a species. After 

 some hundreds of generations in a changed climate the species 

 will revert when conditions again become as they were. " That 

 humidity in some way influences the metabolic processes which 

 lead to pigmentation can hardly be doubted " (p. 5). Uric acid in 

 excess may be a reason, but chemists have not yet settled the 

 question. Local differentiations are transmitted from parent to 

 young, and are hereditary, in the usual sense of that term. " The 

 different factors of the environmental complex do not have any 

 specific influence upon colouration, but all act alike as stimuli, 

 either alone or in combinations, to accelerate or retard colour 

 development, and thus to modify colouration in the following 

 way : — 



" a. — Towards melanic or albinic conditions, which are most 

 general and important in colouration. 



" b. — Towards suppression or accentuation of particular 

 colour areas or groups thereof. 



" c. — Toward changes in the colours themselves," 



Prof. Davenport speaks of black plumage as a " discontinuous 

 characteristic," and one that cannot be modified or is capable of 

 becoming an intergrade. Mr. Beebe quotes diverse views of 

 competent biologists, and remarks upon how little we actually 

 know, not only of the direct action of the various climatic factors 

 of the environment, but of the relative importance of these 



