THE AMERICAN MUSEUM JOURNAL 



It is a law among birds that the adults undergo a complete 

 molt immediately after the cares of the nesting season are over, 

 and that there shall be no further feather-growth until the fol- 

 lowing spring or summer. The Ptarmigan, however, obey only 

 the first portion of this law. In response to what are evidently 

 imperative physiological demands they molt directly after the 

 nesting ; but if they were to pass at once into their winter plum- 

 age, as is customary among birds, they would become pure white 

 before snowfall and hence be made conspicuous by the ])lumage 

 which is designed to protect them. 



To bridge over the period between the normal, postnuptial 

 molt and the season of snow, an additional plumage is assumed 

 on the exposed parts of the body (group No. 4). This is worn 

 only during late summer and early fall and is immediately suc- 

 ceeded by the winter plumage. The changes in the nature of 

 the birds' surmundings are, therefore, as it were, iinitated by the 

 birds, which consequently are always difficult to see in the tree- 

 less regions they inhabit. 



NEWS NOTES. 



HREE new fossil specimens of interest liave been 

 placed on exhibition in the hall of Vertebrate 

 Palasontolog^'. One is the skull of a Duck-billed 

 Dinosaur, an immense biped reptile nearly forty 

 feet in length. The skull is three feet ten inches 

 long and has a broad fiat beak like that of the spoon-bill duck. 

 This skull is part of a nearly complete skeleton which is being 

 prepared for exhibition. The second specimen is the skull of a 

 Mammoth of the largest size, with tusks measuring thirteen feet 

 in length around the outside of their curvatures, probably the 

 longest pair ever found. This specimen came from southern 

 Texas, and is of a larger species than the Siberian nianimi illi. The 

 third consists of the fore and hind limbs and a cast of the skull 

 of the Diprotodon, an extinct Australian mammal of gigantic 

 size. Like all the other Australian mammals it belonged to the 

 Marsupial or l^nichcd division. 



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