Bean-Goose 



113 



are preserved also in East Siberian representatives of the bean and yellow-billed geese 

 (M. segetum serrirostris and M. arvensis sibiricus), as we see from the description of 

 the latter. 



The nail of the upper mandible in M. segetum is narrower and sharper than 

 in M. arvensis. The upper mandible between the posterior edge of the nail and a 

 line uniting the anterior angles of the nasal depressions is nothing like so depressed 

 in M. segetum as in M. arvensis, but rises like a roof, so that, as seen from the side, 

 this part of the bill in the former is higher (thicker) than in the latter species. 



The same may be said of the basal part of the culmen, which is less flat in the 

 bean than in the yellow-billed goose. The lower mandible in M. segetum is perceptibly 

 more arched, while its greatest depth, seen from without when closed, is not only 

 comparatively but absolutely greater. The nasal depressions, according to Naumann, 

 are comparatively shorter, and the nasal apertures smaller, although having a wider lumen 

 in their posterior part. 



M. segetum, £ 

 Culmen 60J mm. 

 (Northern Russia.' 



M. arvensis, <$ 



Culmen 66 mm. 



(St. Petersburg.) 



M. arvensis, % 



Culmen 70 mm. 



(Ryazan.) 



In reality, then, the differences in the structure of the nares, pointed out by Naumann, 

 are very minute, and, although they cannot be denied, are insufficiently marked to serve 

 as trustworthy characters in distinguishing between these two geese, and particularly in the 

 case of dry skins, when in consequence of shrinking the form of both the nasal depressions 

 and the apertures changes so much. 



In regard to the number of teeth in the upper mandible, on which Naumann insists 

 when distinguishing these two geese, I must say that at first I fully shared the view 

 of this ornithologist, as when examining all the bean-geese at my disposal I found 

 that there were from 20 to 21 on each side of the upper mandible. But the specimens 

 of M. segetum brought by Mr. Buturlin from Kolguev in 1902, and the geese of the 

 same species obtained by Mr. Pike in Holland in January 1903 and sent to the British 

 Museum, showed that the number may reach 24, or perhaps even 25. In my 

 opinion, as stated in the Introduction and elsewhere in this volume, the majority 



Q 



