214 MERGANSER CASTOR. 



a half inches in diameter, and four inches in depth. There 

 are seldom more than seven or eight eggs, which measure 

 two inches and seven-eighths in length, by two inches in 

 breadth, are of an elliptical form, being nearly equally 

 rounded at both ends, smooth, and of a uniform dull cream 

 colour." 



The young, at first covered with down of a greyish colour 

 on the body, and reddish on the head, betake themselves at 

 once to the water, and are tended by their mother with the 

 greatest care, the male having deserted her after incubation 

 commenced. In the end of October numbers arrive in Britain 

 from other countries, many remaining during the winter. 

 Those which harbour in the southern parts return northward 

 by the end of April. 



Young. — In their first winter, the young of both sexes 

 resemble the female, having the colours of the plumage as 

 well as the crest similar, the males distinguishable from the 

 females only by their greater size. 



Progress toward Maturity. — In its second year, the 

 male is still similar to the female, with the exception of hav- 

 ing the breast of a beautiful pinkish-buff, as in the adult, the 

 sides under the wings partially marked with grey lines, the 

 smaller wing-coverts of a paler grey, the white secondary 

 coverts greyish-black at the base, and grey at the end. At 

 the next change the plumage is completed. 



Remarks. — It was long supposed that the young males 

 and the females of this bird formed a distinct species, to 

 which the names of Mergus Castor and Dun Diver were 

 given. It is certainly very extraordinary to find an adult 

 male with a crest broad and comparatively short, while in 

 the females, and even the young of both sexes, it is narrow 

 and elongated. But repeated observations and dissections 

 lead to the conclusion that the Dun-Diver and Merganser are 

 specifically identical. 



The female of Merganser Castor may be distinguished 

 from that of Merganser Serrator by attending to the following 



