76 University of Calif ornim Publications in Zoology ["Vol. 30 



The distinguishing feature between the two is color. The adult 

 male of rkhwrdsonii is grayish in general appearance with some light 

 brown mottling on back and sides. In flemingi the brown markings 

 are much reduced and of a darker shade; in general appearance the 

 fully adult male bird is almost black. In the adult female and in 

 immatures (natal down and juvenal plumage of richa»rdsonvi not 

 seen), corresponding differences exist. In most cases the distinc- 

 tions between the two subspecies are evident upon the most cursory 

 examination, and with the exception of one specimen they are uni- 

 formly maintained throughout the series at hand. The exception is 

 an immature female of flemingi (no. 44665, head of Surprise Lake, 

 Atlin region, September 14, 1924), which is much paler than others 

 from the same general region, and hardly to be distinguished from a 

 selected specimen of richardsonu from southern British Columbia. 

 This bird may be taken to exemplify intergradation by individual 

 variation between the two subspecies. 



The sequence of plumage-changes with age in the grouse of the 

 genus Dendraffapus is sufficiently complicated to be difficult to follow, 

 and extensive series of specimens are needed to trace the different 

 stages. An understanding of the development of the individual bird 

 is, however, absolutely necessary in order to avoid mistakes in making 

 comparisons between the several forms included in this group. 



Tailing the subspecies flemingi as a basis, the following stages may 

 be described as indicating the course of development followed in these 

 grouse. Dates given apply to conditions in northern British Columbia. 



Natal down : Sexes alike. There is no specimen of flemingi at hand 

 entirely in the down, but coijparing small young, still down-clothed 

 on head and breast, with specimens of sitken^sis and fuliginosus at the 

 same stage, young flemingi is seen to be much less yellow, more gray, 

 than are the young of those forms. 



Juvenal : Again much more gray than in sitkensis and fuliginosus. 

 Rectriees and remiges begin to appear a few days after hatching, and 

 the young birds are able to fly long before the natal down is all lost. 

 The head and neck are the last parts to be clothed in feathers, as shown 

 in a specimen collected July 8. There is continuous replacement of 

 plumage on the wings from the time the bird is hatched until it has 

 finally completed the post- juvenal molt and is practically full grown. 

 As shown by specimens of young flemingi and of other subspecies also, 

 there are two complete sets of primaries, secondaries, tertials, and 

 greater coverts, at least, acquired during the juvenal stage. The 



