184 CLANGULA CHRYSOPHTHALMA. 



Mr. Audubon considers Clangula Barrovii as C. chrysoph- 

 thalma in summer ; but to this opinion it may be objected 

 that the Litter has been found at that season -with its white 

 spots the same as in winter. In my opinion these crescent- 

 spotted individuals are young males in their second or third 

 year. All their alleged distinctive characters seem to me to 

 countenance this idea. The bill is said to be shorter and 

 narrower, as it surely would be in a young bird ; the head is 

 glossed Avith purple in place of green, as we see to be the 

 case in very many birds, Quiscali, Icteri, and Swallows, for 

 example, toward the end of summer ; the black bar on the 

 wing may depend upon the abrasion of the tips of the coverts ; 

 the black tips of the posterior lateral feathers I have seen in 

 many individuals of the common kind ; there being fewer of 

 the small wing-coverts white indicates apparently that the 

 individual is young ; and the crescentic white spot diifers from 

 the common form only in having the upper part elongated. 

 The enormous enlargements of the trachea in the male of 

 this species, seems to indicate an affinity to the Mergansers, 

 which is moreover somewhat apparent in the form and habits 

 of the bird ; but of what use they can be in the economy of 

 the individual, it seems in our present state of knowledge 

 impossible to discover. They cannot have reference to diving, 

 or the retention of the breath, as they do not exist in the 

 female, which dives as well and as long as the male. We 

 may conjecture that they refer to the voice, both in this and 

 the other ducks and mergansers. In those species, the Geese 

 and Swans, in which the males do not differ from the females 

 in the form of tlie windpipe, the voice is the same in both 

 sexes ; but in birds like this, the voice of the male is more 

 raucous and less loud than that of the female. Dr. Latham 

 errs when he remarks, " whatever share the structure of this 

 singular kind of trachea may have in promoting the loudness 

 of the voice, I w^ill not here insist on ; but it is notorious that 

 the cry is heard further off than many others of the genus." 

 Now, the cry of this bird is a mere grunting croak, and is 

 never heard to any considerable distance ; and the epithet 

 clangula given to it by the earlier ornithologists had reference 

 not to its voice, but to the whistling of its wings. 



