Thick-billed Goose 131 



To this description and dimensions I may add the following remarks : In the 

 first place I direct attention to the fact that in the three specimens of this goose at 

 present known to me, the yellow or orange colouring (or perhaps dark-flesh) forms not 

 only a broad ring embracing both mandibles in the apical portion, but stretches more or less 

 far backwards, under the nostrils, in irregular patches, in a manner I have not once observed 

 in either M. segetum serrirostris or M. arvensis sibiricus. 



Secondly, although the proportion of the nail as seen from above to the total length 

 of the culmen in the specimen in the British Museum and in the male from Bering Island 

 is the same as in M. segetum serrirostris {i.e. the nail is contained in the total length of the 

 culmen 2>\ times), in the example from Northern Manchuria the nail is somewhat shorter 

 and more rounded and occupies only a little less than one-fourth of the total length of the 

 culmen, so that in form and relative size it somewhat approaches M. arvensis sibiricus. 



Lastly, while the number of teeth in the example from Japan and in the Manchurian 

 specimen is 25, Stejneger definitely states that in the male from Bering Island the number 

 was 20, or that which is most commonly met with in M. segetum serrirostris. 



On the strength of these three specimens it would seem, then, that the characters 

 of the bill in M. mentalis are not constant. 



At first these considerations led me to think that perhaps we have to do with 

 hybrids between M. segetum serrirostris and M. arvensis sibiricus, although I thought 

 it could not be admitted that the crossing of the former with the long-billed M. arvensis 

 sibiricus would yield a breed with such a large and massive bill as is seen in the thick- 

 billed goose. 



Now, however, on the grounds stated at the end of the notice on the Siberian 

 bean-goose, I have almost abandoned this hypothesis, and am rather inclined to see in 

 these thick-billed geese only very old individuals of the Siberian bean-goose which have 

 reached the limit of their growth. I even think that perhaps all such thick-billed geese 

 will prove to be exceptionally old ganders of this species. 



The question, then, as to whether M. mentalis constitutes an independent species 

 or only a large form of the Siberian bean-goose still remains open. 



Mr. Oates writes as follows on this goose : " On looking over the geese in the 

 British Museum, I was struck by the large size of one of the specimens, its massive 

 bill and white chin. It came from Yokohama, and was once in the Seebohm Collection. 

 I can only regard this goose as a species which has not before been noticed, and I 

 accordingly give it a distinguishing name. . . . There is nothing on the label of the 

 specimen to show what the colour of the bill and legs was in life." 



I may add that I have previously pointed out that one of the characters given by 

 Mr. Oates, namely, the white chin, is not distinctive of this goose; so that beyond the 

 massiveness of the bill and the great dimensions of the bird itself there are no sufficient 

 characters to justify its right to specific independence. 



Geographical Distribution 



At present we know for certain three countries where the thick-billed goose has 

 been found, namely, Japan, Bering Island (in the Komandor group), and Inkow in 

 Northern Manchuria, where the example now preserved in the musetim of the St. 

 Petersburg Academy of Science was obtained on February 27, 1901. 



