412 Recent Literature. \jO^ 



The half-tone pictures, nearly one hundred in number, add immensely to 

 a clear conception of the breeding haunts and habits of a large number of 

 species the ordinary observer can hardly hope to be able to study in 

 life. — J. A. A. 



Witherby on the Migration of Birds.' — Mr. Witherby sets forth at 

 some length, in a popular way, many well-known facts about bird migra- 

 tion. "None of the many theories " professing to answer the questions 

 of what causes migration, what first led birds to migrate, and how they 

 find their way, are, to him, in any way satisfactory ; "the more," he says, 

 "we study the matter, and the more we learn, the more difficult does it 

 become to adopt any of the theories, fascinating and plausible though 

 many of them are." But he believes that the collecting and sifting of 

 information, now going on, "will lead us almost imperceptibly towards 

 the discovery of this mystery of mysteries"! When discovered, what an 

 aching void there will be for those who love mysteries! — J. A. A. 



Shufeldt on the Osteology of the Psittaci.^ — The views of several lead- 

 ing authorities on the classification of the Psittaci are quoted at some 

 length (pp. 399-405), and then follows an account of the osteological 

 characters of the Carolina Paroquet, this part of the paper being a revi- 

 sion, with some additions, of his paper on the same subject published in 

 1886, to which is added (pp. \\(), 420) 'Observations upon the Osteology 

 of the Owl Parrot (Stringops habroftilus). The nine figures forming the 

 four half-tone plates represent the skeleton of Stringops and the skulls of 

 Conurus carolinensis, Ara niilitaris, and Cacatua galerita, and the trunk 

 skeletons and some other bones of Co7iurtisz.x\6. Cacatua, the sternum and 

 shoulder girdle of Calyptorhynchus, and the humeri of Cacatua. — J. A. A. 



Strong on the Metallic Colors of the Feathers of the Neck of the 

 Domestic Pigeon.^ — The so-called metallic colors and iridescent eftects 

 of feathers have been generally explained as diffraction phenomena. Dr. 

 Strong states that the hypothesis based on the supposed presence of stria; 

 and ridges is "inapplicable to this case when one finds that the feather 

 may be rotated through a whole circle with essentially the same color 

 effects for given angles even from individual barbules. Furthermore, a 

 careful microscopic study of the barbule surface shows that irregularities 



' The Migration of Birds. By H. F. Witherby, F. Z. S., Member of the 

 British Ornithologists' Union. Separate, pp. 16, reprinted from ' Chambers 

 Journal.' 



- Osteology of the Psittaci. By R. W. Shufeldt. Annals Carnegie Museum, 

 Vol. I, 1902, pp. 399-421, pll. xxi-xxiv. 



^The Metallic Colors of Feathers from the Neck of the Domestic Pigeon, 

 By R. M. Strong. Biolog. Bull., Vol. Ill, 1S92, pp. 85-87. 



