Chap. XVI.] CLASSES OF CASES. 179 



RULES OR CLASSES OF CASES. 



I. "When the adult male is more beautiful or conspicu- 

 ous than the adult female, the young of both sexes in 

 their first plumage closely resemble the adult female, as 

 with the common fowl and peacock ; or, as occasionally 

 occurs, they resemble her much more closely than they do 

 the adult male. 



II. When the adult female is more conspicuous than 

 the adult male, as sometimes though rarely occurs, the 

 young of both sexes in their first plumage resemble the 

 adult male. 



III. When the adult male resembles the adult female, 

 the young of both sexes have a peculiar first plumage of 

 their own, as«vith the robin. 



IV. When the adult male resembles the adult female, 

 the young of both sexes in their first plumage resemble 

 the adults, as with the kingfisher, many parrots, crows, 

 hedge-warblers. 



V. When the adults of both sexes have a distinct 

 winter and summer plumage, whether or not the male 

 differs from the female, the young resemble the adults 

 of both sexes in their winter dress, or much more rarely 

 in their summer dress, or they resemble the females alone ; 

 or the young may have an intermediate character ; or, 

 again, they may differ greatly from the adults in both 

 their seasonal plumages. 



YI. In some few cases the young in their first plumage 

 differ from each other according to sex ; the young males 

 resembling more or less closely the adult males, and the 

 young females more or less closely the adult females. 



Class I. — In this class, the young of both sexes re- 

 semble, more or less closely, the adult female, while the 

 adult male differs, often in the most conspicuous manner, 

 from the adult female. Innumerable instances in all Or- 



