ii4 Geese of Europe and Asia 



of the bean-geese at first examined were young birds, while among the specimens brought 

 by Mr. Buturlin the number 24 occurs exclusively in old birds. 



Among the eight Kolguev geese, in one example there are 20 teeth on each 

 side of the upper mandible; in two, 21; in one, on one side 21, on the other 22* 

 in two, on one side 22, on the other, 23 ; and in two, 23 on one side, and 24 on the 

 other. 



Of the four bean-geese from Holland mentioned above, according to Mr. Frohawk 

 two examples had 21 on each side; in one, there were 21 on the right side and 22 on 

 the left ; and finally in one gander there were 24 teeth on each side. 



On finding that the Kolguev geese had such a number of teeth, I thought this 

 apparent anomaly might be ascribed to the interbreeding in Kolguev between yellow- 

 billed and bean-geese ; but I no longer hold this opinion, as I have found a similar 

 variation in the number of teeth in other geese. 



On the whole, I may say that as the number of teeth is not constant, it cannot 

 be considered as an absolutely good distinctive character to differentiate the bean- 

 goose from the yellow-billed species, but it may yet serve as an auxiliary character in 

 discriminating between young birds of these two species, in which the pattern on the bill 

 is very similar. 



Accordingly, if we see a young goose of this group with 20 or 21 teeth on each 

 side of the upper mandible, we may be almost certain that we have to do with M. segetum, 

 and the further examination of the bill, that is, the relation of the nail to the culmen- 

 length, will not fail to confirm this ; in like manner, if we have a young goose with 

 24 or 25 or more teeth on each side of the upper mandible, we may safely assert that 

 it is not Ж segetum. 



If we add to this difference in the bills of these two species the fact that, in the vast 

 majority of cases, in M. segetum the yellow or yellow-orange colouring 1 is concentrated on 

 the apical part of the bill, while in M. arvensis it prevails over the black (I here speak 

 of adults), I think these differences will suffice (when taken together) to discriminate 

 with complete certainty between the bean and the yellow-billed goose, in spite of the 

 considerable degree of individual variations to which the bills of these two geese are 

 subject. 



The figures of the bills of these two species given on Plate 23 of this work show 

 these differences still more clearly, and, I hope, will serve in the future to remove the 

 confusion which has reigned in this group of geese for more than a century, notwithstanding 

 the clear explanation of their differences given by Naumann in 1842. 



In conclusion, I may refer to the question whether specimens of the bean-goose 

 ever occur in which the colouring of the yellow-orange band on the upper mandible extends 

 beyond the nasal apertures and stretches more or less back along the tomia. No such 

 examples have ever come into my hands, but that they do occasionally occur is demonstrated 

 by a sketch by Mr. Frohawk of a bill of this type from a goose killed in England, and 

 also from the fact that similar individuals have been brought by Mr. Buturlin from 

 Kolguev. 2 



1 For the colouring of the bill in this species, see Appendix entitled " Novaia Zemlia Bean-Goose." 



2 Since this was written, my son shot a specimen of this species in the mouth of the Neva, in April 1904, with the yellow colour 

 on the bill extending far back under the nostrils. 



