1 5 ° Bicknell on Hylocichla alicice bicknelli. 
mens of true alicice that I have seen, and this little most evident 
low down where the corresponding shade in swainsoni begins to 
pale. It seems probable that this newly recognized race of alicice 
is responsible for much of the ambiguity which the discussion of 
both species by different writers has occasioned. Indeed, it seems 
to occupy the same pQsition relative to alicice proper which, by 
some, sxvainsoni was supposed to hold, viz., the more southern- 
born individuals of the species, but that it represents a link spe- 
cifically connecting the two, the facts already presented refute. 
As it occurs with true alicice on the autumn migration most 
specimens of the new form are paler and more brownish in color 
above, and their general size is nearly that of swainsoni A and 
these differences may be regarded by some as approaches towards 
the latter species. In both species there is a wide individual var- 
iation, but the closest approach of each towards the other never 
exceeds that limit within which each may vary without its spe- 
cific distinctness being compromised. I have yet to see a speci- 
men of either which would admit of the slightest question as to its 
identity. I speak thus of adult birds. In such closely related spe- 
cies the young must almost necessarily approximate, and to these 
we must appeal for light on the things that have been — on the 
question of origin — whether one has been derived from the 
other, or both species from a common ancestor. Such obscure 
insight into this point as I have been permitted seems to indicate 
that the latter alternative will be found to be the more correct, 
but, for the present, from lack of the necessary data this impor- 
tant subject is proscribed. 
It is unnecessary here to repeat the diagnosis of the new form 
of Hylocichla alicice given by Mr. Ridgway in the paper before 
cited. As this writer states, the race breeds “‘probably in other 
mountainous districts of the northeastern United States” than the 
single locality where it was discovered, and it seems very singular 
that up to the present time we have no knowledge of its occur- 
rence in the summer season elsewhere, even in regions where the 
two congeneric species with which it was here associating — H. 
* Though averaging of greater length, in proportions this bird averages smaller than 
swainsoni, and some specimens are much smaller than any I have seen of the latter 
species. The wide difference from true alicice here implied may be illustrated by the 
following extreme measurements given by the birds of my series : — 
alicice, length, 8.00; extent, 13.12 ; wing, 4.35 ; tail, 3.40. 
bicknelli, “ 6.55 ; “ 10.56 ; “ 3.40 ; “ 2.60. 
