Yellow-billed Bean-Goose 



97 



Sex. 



Culmen. 



Depth of lower 

 mandible, seen 

 from without, 

 with bill shut. 



Number of teeth 

 on each side of 

 upper mandible. 







mm. in. 



mm. in. 







? 



594 = 2 -34 



7 =0.27 



24 



Moscow, Prof. M. A. Menzbier's coll. 



9 



59 =2-32 



7 -0.27 



26 



N 



? 



66 =2.59 



71 = 0.29 



25 





?, 



55 =2.16 



7 =0.27 



24 



. 



? 



6 5 =2.55 



8 =0.31 



25 



Ryazan, collected by Khomyakov, who took some of the specimens 



cJ 



54 =2.12 



7 =0.27 



25 



for M. middendorffii, Sev. 



6 



70 =2.75 



7 =0.27 



28 





6 



67 == 2.63 



8 =0.31 



25 





в 



64 =2.51 





? 



J 



6 



65 =2.55 





? 



Chinaz, Severtsov's coll., Zool. Mus. Ac. Sci., St. Petersburg. 



? 6 



68 =2.67 





24 



Fergan district, Severtsov's coll., Zool. Mus. Ac. Sci., St. Petersburg. 



6 



62 = 2.44 





? 



Thian-Shan (West), Severtsov's coll., Zool. Mus. Ac. Sci., St. Petersburg. 



? ? 



62 = 2.44 





? 



Chimkent, „ „ 



0* 



62 = 2.44 



7 =0.27 



? 



» •>•> fi 



6 



67 = 2.63 



81 = 0.33 



? 



a 35 »j 



6 



6l == 2.4О 



? 



? 



Chinaz, ,, ,, 



6* 



64 =2.51 



? 



? 



Fergan district, ,, ,, 



s 



?■ 



7 =0.27 



? 



33 J> 33 



в 



72 =2.83 



8| = o. 33 



26 



Chimkent, Severtsov's coll., Zool. Mus. Ac. Sci., St. Petersburg — 

 biggest example of Severtsov's coll., and probably original of his 



M. middendorffii. 



? (J 



70 =2.75 



? 



24 



Chimkent, Severtsov's coll., Zool. Mus. Ac. Sci., St. Petersburg. 



6* 



66 =2.59 



? 



? 



Kharkov government, N. N. Somov's coll., Zool. Mus. Ac. Sci., St. 

 Petersburg. 



6* 



63 -2.48 



? 



? 



53 33 3) 



<J 



66 -2.59 



7 = 0.27 



26 



Petersburg gov., from A. P. Semenov (my coll.). 



* 



65 =2.55 



8 =0.31 



25 



Belgium (my own coll.). 



6* J uv - 



57 =2.24 



6 =0.23 



24 



Obdorsk, К. M. Deryugin, coll. Zool. Mus. Ac. Sci., St. Petersburg. 



<J ad. 



67 sb 2.63 



7 =0.27 



28 



Zvenigorodsk district (Mosc. gov.), Lorenz, Zool. Mus. Ac. Sci., St. 

 Petersburg. 



? 



62 = 2.44 



7 =0.27 



25 



Tomsk, May 15, 1902, from Prof. Kashchenko ; much yellow on bill. 



? 



58 =2.28 



71- 0.29 



25 



•>•> 33 11 3) 



? 



65 =2.55 



8 =0.31 



26 



44 14 33 33 



juv. ? 



60 = 2.36 



7 =0.27 



25 



53 33 33 3) 



ad.? 



70 =2.75 



8i = °-33 



28 



„ „ (bill passing to sibiricus type; no white 



feathers basally). 



? 



67 =2.63 



8i = o. 33 



28 



,, „ {arvensis type). 



? 



67 =2.63 



3i = o.33 



26 



„ „ many yellow spots all over bill. 



juv. ? 



60 = 2.36 



8 =0.31 



27 



„ „ typical youngster. 



juv. ? 



59i = 2.34 



7 = 0.27 



25 



33 3) 3? 



p 



7iJ = 2.81 

 68 =2.67 

 66 =2.59 

 62 = 2.44 



Lower 



j- mandible -[ 



wanting 



26 



27 

 26 



27 



1 



I Of 1 1 birds of this species, brought in 1902 by S. A. Buturlin from 

 i Novaia Zemlia (Malyya Karmakuly), in all yellow colour on 





bill prevails over black. 



If we compare this table with the one in the notice of M. arvensis sibiricus, we 

 shall see that there is no possibility of identifying either the Ryazan or the Turkestan 

 M. arvensis with the East Siberian M. arvensis sibiricus. 



I must, however, now point out, in regard to the bill, the chief distinctions existing 

 between these two geese. To begin with, I have to dwell in some detail on the description 

 of the bill of M. arvensis, which affords characteristics sufficient to discriminate with 

 absolute certainty between this species and the bean-goose (M. segetum). Before doing so, 

 I ask the reader to note that in this description I have exclusively in view the bills of adult 

 birds. The bill of the yellow-billed goose is considerably more elongated than in M. segetum, 

 from which it also differs in form. It is also longer and comparatively broader at the point, 

 and far more depressed behind the nail of the upper mandible. At the same time the lower 

 mandible in M. arvensis is less curved and comparatively less deep in the thickest part 

 (looking at the shut bill from the side) than in M. segetum. The nail is considerably 



о 



