15*^ BiCKXEi.i. Oil. Hylocichla aliciiv bickjielli. 



mens of true alicuv that I have seen, and this little most evident 

 low down where the corresponding shade in sw a insoni hn'^xn?, to 

 pale. It seems probable that this newly i^ecognized race of alicice 

 is responsible for much of the ambiguity wdiich the discyssion of 

 both species by different writers has occasioned. Indeed, it seems 

 to occupy the same position relative to alicice proper which, b>- 

 some, sxuainsoni 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 autimm migration most 

 specimens of the new form are paler and more browm'sh in color 

 above, and their general size is nearly that of sivai/iso}?i* and 

 these differences mav 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 foriight on the things that have been — on the 

 question of origin — whether one has been deri\'ed from the 

 other, or both species from a common ancestor. .Such obscure 

 insight into this point as I have l)een permitted seems to indicate 

 that the latter alternative Avill lie foimd to be the more correct, 

 but. for the present, from lack of the necessar\- data this impor- 

 tant subject is proscribed. 



It is unnecessarv here to repeat the diagnosis of tiie new form 

 of HylocicJila alicice given liy 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 localitx 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 — 11. 



* Though averaging of greater length, in proportions this bird averages smaller than 

 swainsoiii, and some specimens are much smaller than any I have seen of the latter 

 species. The wide difference from true allcicE 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, " 0.55 ; " 10.56 ; " 3.40 ; " 2.60. 



