Anser erythropus and its Allies. 373 



some difference of habitat, surely such birds ought to be kept 

 asunder. In the ' Catalogue of the Birds in the British 

 Museum/ xxvii. pp. 92-99, the three forms are treated as 

 distinct species by Count Salvadori, who evidently had a 

 good series of skins before him. I think that there is less 

 difference between A. albifrons and A. gambeli than there is 

 between A. albifrons and A. erythropus, but, if a new species, 

 Anser neglectus {cf. Ibis, 1897, plate ii.) can be put in be- 

 tween A. brachyrhynchus and A. segetum, all the three White- 

 fronted Geese ought surely to stand also, from a separatist's 

 point of view. 



Some British-killed examples of A. albifrons are very 

 black indeed on the under surface, and, in fact, have little 

 colour except black on the lower breast and belly. One of 

 these dark examples (killed in Co. Mayo) was sent by 

 Mr. Coburn to a meeting of the Norwich Naturalists' 

 Society along with his A. erythropus, and another is 

 particularly referred to in Ussher's ' Birds of Ireland ' 

 (p. 170) as having been shot at Baronscourt. These Geese 

 may have flown across the Atlantic Ocean, and thus be 

 regarded as veritable A. gambeli, or they may be hybrids. 

 A. erythropus is also very black occasionally, judging from 

 the plate in Bree's ' Birds of Europe,' the only representation 

 of it published in this country, and one which must have 

 been taken from a very black-bellied example. 



It is highly probable that A. gambeli occasionally breeds 

 with A. albifrons, and A. albifrons with A. erythropus, 

 hybrids being thereby produced. The authors of 'North 

 American Birds,' i. p. 450, mention a cross between A. 

 gambeli and Bernicla occidentalis, and M. Suclietet notes 

 another supposed cross between A. albifrons and B. brenta 

 (Ois. hybrides, p. 739) . There are other instances of Geese 

 interbreeding, as at Lilford, where a White-fronted goose 

 paired with a Bean gander (Zoologist, 1894, p. 214), shew- 

 ing that there is nothing at all improbable in a union 

 between any two of the three closely allied White-fronted 

 Geese. 



The following comparative measurements begin with those 



SER. VIII. VOL. II. T 



