The American Museum Journal 



Vol.. III. 



KEllKUARV, 1903 



No. 2. 



HE Guide Leaflet sent out with this number of the 

 Journal describes in popular language the mem- 

 bers of the family of Sphingid^, or "Hawk- 

 Moths," which are to be found in the vicinity of 

 New York City. The arrangement of the species 

 in the Leaflet corresponds with that of the specimens in the cases, 

 and the Leaflet, therefore, forms a convenient guide to the collec- 

 tion. More detailed descriptions of these beautiful and interest- 

 ing moths will be found in Mr. Beutenmuller's article on the 

 Sphingidas which was published in Volume VII of the " Bulletin" 

 of the Museum. 



THE PTARMIGAN GROUP. 



A GROUP, or rather an assemblage of four groups in one 

 case, of the Ptarmigan was placed on exhibition in the Bird 

 Hall on the main floor of the Museum in January. The four 

 small groups together illustrate one of the most interesting cases 

 of seasonal change known among birds. The group has been 

 provided for through the liberality of J. D. Cadwalader, Esq. 



In the summer the birds are brown and black, in the autumn, 

 grayish, and in the winter, white. These changes are accom- 

 plished by molt and feather-growth, not by change in the color 

 of existing feathers, as has been stated by some writers, and are 

 designed to protect the birds from their enemies by keeping 

 them in harmony with their surroundings, and thereby render- 

 ing tliem inconspicuous. It will be observed that the wliite 

 winter birds (group No. i) molt in the spring (group No. 2), and 

 pass directly into summer plumage (group No. 3). 



IS 



