114 Recent Literature. \^l^. 



RECENT LITERATURE. 



Dwight's ' Sequence of Plumages and Moults of the Passerine Birds of 

 New York' J — The present paper is in all respects the most important con- 

 tribution to the study of plumages and moults that has jet appeared, and 

 is in fact a monograph of the subject it treats, which will serve as a stand- 

 ard work of reference for a long time to come. The treatise comprises 

 287 pages of text and seven half-tone plates of photographs and photo- 

 micrographs of feathers illustrating various methods of abrasion, etc. 



The subject of the work is treated under several subheadings, ' Indoor 

 Study of Moult,' ' Process of Moult,' ' Early Plumages and Moults of 

 Young Birds,' ' Sequence of Plumages and Moults," 'Color Facts versus 

 Color Theories,' ' Outdoor Study of Moult,' ' Plumages and Moults of New 

 York Species' (1S8 pp.), 'Bibliography' (27 pp.). 



Under the first of these are considered the fundamental principles of 

 moulting, wear, or feather disintegration, and the determination of age by 

 osteological characters. ' The last is a most important matter which has 

 never before been clearly set forth, but with Dr. Dwight's explanation all 

 collectors should in future be able to distinguish at once between the ' bird 

 of the year' and the adult in every late summer or autumn specimen, 

 and thus add immensely to the value of their materials. The principal 

 point in Dr. Dwight's explanation will bear repetition : "It is simply this, — 

 the prominent frontal bones of the young bird are thin and transparent 

 showing the brain beneath, while those of the adult are thicker and flecked 

 with whitish dots, which show even better as black dots, when, with the 

 brain removed, the skull is held up to the light." The value of the pri- 

 mary coverts as an index of age is also frequently dwelt upon, as they 

 retain the characters of immature plumage longer than any other feathers. 



Under ' Process of Moult ' the various feather tracts of the bird are 

 considered with great detail and it is demonstrated that there is much 

 more symmetry in the moult on the body than had previously been sup- 

 posed. The apparent irregularity is due to the fact that the moult begins 

 almost simultaneously in a number of different tracts, spreading inde- 

 pendently in each of them from a central point or focus. Dr. Dwight 

 aptly likens the progress of this moult to a rising tide gradually spreading 

 over a number of small islands. The length of time required for the 

 complete postnuptial moult is also discussed, a question that has occa- 

 sioned considerable difference of opinion. Dr. Dwight estimates it at 

 about one month to six weeks, as a rule. Under ' Sequence of Plumages 

 and Moults ' is a most careful discussion of this whole subject, resulting 



^ The Sequence of Plumages and Moults of the Passerine Birds of New 

 York. By Jonathan Dwight, Jr. Reprinted from the Annals New York 

 Acad. Sci., Vol. XIII, pp. 73-360, pi. i-vii, Oct. 31, 1900. 



