THE PLUMAGE OF THE GREAT NORTHERN DIVER 143 



white varies : that in typical feathers from the gular band 

 (Fig. 9), white predominates, whilst in typical feathers 

 from the neck-bands, black predominates (Fig. 10). Dr. 

 Elliott Coues ("Key to North American Birds," 5th ed., 

 vol. ii. p. 1049), i^ describing these lateral lines, says, "The 

 white throat-patch consists usually of five or six streaks ; in 

 this, as in the lateral neck-streaks, the individual feathers are 

 broadly black, with sharp white edges towards their ends." 

 Whilst this describes pretty accurately the feathers forming 

 the transverse neck-bands (Fig. i c), it does not give a true 

 description of the feathers forming the gular band (Fig. 9). 

 In these latter, there is only a triangular piece of black at 

 the tip of each white feather. 



There is another point of extreme interest connected 

 with Great Northern Divers. I refer to the nature of the 

 feathers covering the head and neck during winter plumage. 

 These feathers, in winter, are of a downy nature, in great 

 contrast to the strong true feathers found on the head and 

 neck in summer plumage. This downy state of the feathers 

 seems not to be confined solely to the Great Northern 

 Divers, as, upon examination, I find the same state of affairs 

 appertaining during the winter feather, in an equally marked 

 degree in the Black-throated Divers, and in a somewhat lesser 

 degree in the Red-throated Divers and the Cormorants. 



On examining the Alcidce there is also an appreciable 

 difference in the structure of the feathers on the head and 

 neck in winter and summer, those in winter being of a more 

 downy nature than those in summer, but it appears to be 

 only in two species of the Colymbidce that these winter 

 feathers are of a purely downy nature. This downy nature 

 of the feathers must not be put down to immaturity, as it is 

 characteristic of the fully adult bird in winter plumage, and 

 was, I believe, first noted in print by Mr. J. L. Bonhote 

 ("Birds of Britain," p. 384). 



On reviewing the whole matter one is at once struck 

 by the analogy between the changes of moult seen in the 

 Great Northern Diver, and the changes noted in the spring 

 moult of some of the Anatidae, for example the Long-tailed 

 Duck (//. glacialis). 



In both we notice : — 



