loo Geese of Europe and Asia 



and a patch on the culmen, is entirely yellow-orange, only the rami of the lower mandible 

 being more or less black, as is also the nail. Sometimes, however, the black stretches along 

 the basal half of the edge of the upper mandible, and sometimes black patches of indefinite 

 shape are scattered here and there over the yellow-orange ground of the bill. The basal half 

 (or somewhat more) of the rami of the lower mandible is also at times black, but between 

 this black and the nail the lower mandible is invariably yellow-orange, this latter colour 

 intersecting also the apical part of the naked skin of the chin. In proportion as the length 

 of the bill increases, so far as I have been able to ascertain from the material at my disposal, 

 the black more and more dislodges the yellow from the base of the bill ; and once the bill 

 attains a culmen-length of 70 mm. ( = 2.75 in.), it is safe to say that the whole base will be 

 entirely black ; thus to a certain extent indicating the transition to the East Siberian 

 M. arvensis sibirictts. This, in its general features, is the arrangement of the yellow-orange 

 and black colouring on the bill of M. arvensis. 



I may now direct the special attention of the reader to the fact that in young birds of 

 typical M. arvensis the yellow-orange colouring never has such a great extension as in old 

 birds, and that often in birds of the second and third years (according to my estimate) the 

 greater part of the bill is wholly black ; so that only a broad ring in the apical part of the 

 bill and a wedge-shaped space passing from it backwards under the nares resemble the 

 pattern on the bill of the bean-goose. It is, then, such immature specimens of the yellow- 

 billed goose that have evidently been taken by various authors for M. segetum, thus giving 

 rise to that confusion in the literature it is so difficult or even impossible to put right. 



It must also be borne in mind that in some individuals the yellow-orange colour is 

 scattered over the black ground of the basal portion of the bill in irregular sharply defined 

 patches. Such examples I hold to be transitional to the fully adult, and they should eventu- 

 ally assume the colouring of typical specimens, which I have described above, and. have 

 figured in Plate 23 of the present work. 



After death the orange colour often takes a deep red tinge, which must be ascribed 

 to subcutaneous extravasation or infiltration of blood. In living birds, however, the depth 

 of the yellow or yellow-orange colouring is, apparently, subject to considerable variation, 

 directly dependent, I think, on the quality of the food taken by the bird, and its condition, as 

 I have also stated in the notice of the genus Anser. 



The bare parts of the eyelids in this species are reddish grey ; the legs yellow-orange, 

 with lighter webs in full adults and greyish dull yellow webs in young birds; claws black, 

 but occasionally also whitish. It was evidently examples of the latter type which were 

 described by Baron Selys de Longchamps Y as M. arvensis, var. lemony x ; but the author him- 

 self afterwards acknowledged this form to be merely an accidental aberration from the type. 

 Occasionally it happens that only the outer toe has a whitish claw, while the rest are black. 



The iris is dark brown. 



Geographical Distribution 



In spite of the confusion between this goose and the bean-goose, we are somewhat 

 better acquainted with its range than with that of the latter. The present species is 

 evidently, on the whole, far more numerous than the bean-goose, and the region of its 

 nidification is larger both in longitude and latitude. This goose breeds from 64 N. lat. 

 upwards in the Scandinavian peninsula and in that of Kola, as well as in the greater part 



1 Naumannia,) 1856, s. 394. 



