12 Zoologia: N. Y. Zoological Society. [Vol. 1 



mans, but they are now recognized as only a color phase. In 

 distinction to the others they have a white ring around the eye 

 and a white stripe leading back from it. No intermediate types 

 are known; the murres either possessing the circle and stripe 

 fully developed or being wholly without it. On our coast the 

 murre breeds along the sea-cliffs from Nova Scotia northward. 

 It is said that in the Californian subspecies this white phase is 

 never found, although it is present in birds of Europe and Asia. 



The status of Chen hyperboreus and C. caerulescens, the 

 snow and the blue goose, has long been a puzzle to systematists. 

 C. hyperboreus is pure white in color with black tips to the pri- 

 maries. The immature bird closely resembles C. caerulescens, 

 having a light head and neck, but with all the upper body plumage 

 dusky or bluish-gray. For many years the blue goose was 

 thought to be merely the young of C. hyperboreus, but ultimately 

 both were considered to be true species, and in the check-lists 

 to-day are so listed. But word comes indirectly from Prof. F. E. 

 Blaauw, of Holland, that he has obtained C. caerulescens from 

 eggs laid by C. hyperboreus, and vice versa. This would indicate 

 that, if indeed the two geese breed true and by themselves in the 

 Arctic regions, one of the forms is of comparatively recent 

 origin. We know nothing of the nest and eggs in nature of 

 C. caerulescens except from the report of the Esquimo that its 

 home is in the inaccessible humid bogs and swamps of the in- 

 terior of Labrador. It is said that the blue goose "crosses James 

 Bay, in the southern part of Hudson Bay, coming from the east- 

 ern coast, while the snow goose comes down from the north, 

 seeming evidently to indicate that their breeding places are dis- 

 tinct." 



If the various facts above related concerning these two 

 forms of geese are correct, and if the intra-specific occurrence 

 of such dichromatic phases as these, adumbrates new and perma- 

 nent forms, we have an interesting and significant stage of 

 species formation by geographical variation. The status of the 

 forms of Chen may, from such a point of view, be considered as 

 somewhat more advanced than the condition in Gallinago, Archi- 

 buteo, and, as we shall see later, in Felis pardus. 



Although, and this is an important point, while in these 

 latter forms the dark phase of distributional variation is subordi- 

 nate to the normal type, and at the same time congenital and of 

 recent evolution — perhaps an incipient species — in the case of 

 Chen the fact that hyperboreus in its immature plumage closely 

 resembles caerulescens would seem to indicate that the latter 

 phase — or species — is the more primitive and ancient, and is per- 



