Plates. Plate I.-Skull of Macrogeomys cherriei (Allen). Plate IV. Skulls of the Long-horned Titanotheres. Plates V-IX-Temple of Tepoztlan. Plate X.-Head of Rangifer terrænovæ. Plate XI.-Antlers of Caribou. Plates XII-XIV.-Fossil Crustaceans, of the genera Entomocaris and Ceratiocaris. DATES OF PUBLICATION OF AUTHORS' Art. I, March 4, 1896. Art. II, March 5, 1896. Art. III, March 18, 1896. The edition of authors' separates is 100 copies or more (frequently 150, scmetimes 200 or more). Besides the authors' separates, and in addition to the regular edition of the Bulletin, 100 copies were issued in signatures as printed, each signature bearing at the bottom of the first page the date of publication, BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY. Volume VIII, 1896. Article I. THE CHANGES OF PLUMAGE IN THE DUNLIN AND SANDERLING. By FRANK M. CHAPMAN. One of the most interesting chapters in Gätke's notable work 'The Birds of Heligoland' is entitled 'Changes in the Colour of the Plumage of Birds without Moulting.' Herein Herr Gätke tells us that for over forty years he has given "the most unremitting attention" to this subject. As a result he presents us with three explanations of the manner in which a bird may pass from winter dress into full breeding plumage without molting. Briefly, they are the following: First, by "shedding the edges of the feathers...." Second, by "a peeling off of the separate barbs of the feathers, whereby these are stripped of a thin inconspicuously coloured envelope, so that the purer and finer colour previously concealed beneath the latter becomes exposed....... Further, the feathers, which by the end of winter were worn irregularly, and blunted at the tips, after this change of color, again have their margins completed, and their tips beautifully and evenly rounded off, so that they are in all respects like perfectly new feathers, such as would be produced by moulting." The third process is the "most wonderful," and [March, 1896.] [1] 1 "consists in an actual, complete, and very striking change in the colour of the feathers, without such alteration being brought about, or even assisted, by any changes in their texture." The examples cited as illustrating this change are the Little Gull, Guillemots, and Razor-billed Auk, in which the head and neck change from white or whitish to slaty black or blackish brown ; the Dunlin, in which the upper belly changes from white to black, and other species. The first explanation given by Herr Gätke is well known to occur in many species, and calls for no special remark in this connection. The second and third are, in part, original with him, and the evidence which he presents in their support is derived entirely from his own observations.. Probably owing to our comparative ignorance of the molt of birds and its attendant phenomena, these statements of Herr Gätke's have not only passed unchallenged, but have actually been endorsed as correct. Already we find that they have become part of the literature of general ornithology, and we read of the renewal of the worn tips of feathers and repigmentation as though they were established facts. Herr Gätke describes in some detail the manner in which the changes of color previously mentioned occur. He does not, however, tell us just how his conclusions were reached, whether by the examination at one time of large series of specimens, or at intervals upon occasional specimens during the forty years which he has devoted to the subject. This, of course, is a matter of some importance, as every one who has studied the molt knows, and it seems to me that before accepting Herr Gätke's views they should be thoroughly tested by a study of series of specimens representing the species he mentions. As a contribution to this end I offer the following notes on the changes in plumage of the Dunlin (Tringa alpina) and Sanderling (Calidris arenaria), two species from which Herr Gätke obtained “surprising results." The Dunlin may, I think, be quickly disposed of. It will be remembered that in winter plumage this bird is almost uniform brownish gray above, the breast is washed with the same color and indistinctly streaked with blackish, the throat and belly are |