1 86 Geese of Europe and Asia 



In the Zoological Museum of the Academy of Science at St. Petersburg are three eggs of a large 

 goose from Eastern Siberia, undoubtedly belonging to one of these two species, 1 but to which I am, of 

 course, unable to say — although, probably, to the larger of the two, since these eggs are very large and, 

 although of the same size, are comparatively much lighter than those of A. anser. 



The structure of the shell of eggs of species akin to Anser or Eulabeia indica, Chen hyperboreus, 

 Cygnopsis cygnoides, and the group of black-legged species must, I think, be like that of the aforesaid 

 groups. The grain of the shell in these groups may be characterised somewhat as follows (seen under a 

 glass magnifying six times) : — 



(i) The grain of the shell in the eggs of the large bean-geese (Melanonyx) shows conspicuous eleva- 

 tions, surrounded and severed from each other by wide zones, or coronae, of very irregular 

 outline, as it were deeply eroded out of the shell. 



(2) The grain of the shell in the white-fronted species produces the impression, when looked at with 



the naked eye, of rather coarse marble. Under the glass, the surface, which seemed fairly 

 smooth, is seen, however, to consist of a mass of elevations thickly crowded on each other. 



(3) The grain of the shell of the eggs of the snow-geese (Chen) resembles that of the white-fronted 



geese, but the elevations are more noticeable and do not stand so close together. There is 

 accordingly sufficient space between them to permit of their becoming soiled, as may be seen in 

 the egg belonging to the Zoological Museum of the Imperial Academy of Science at St. 

 Petersburg. 



(4) The grain of the shell in the eggs of the grey-lag {Anser anser) looks as if an originally very 



coarse shell had been subjected to careless polishing ; traces of the eroded portions remaining 

 on the shell in the shape of short serrated lines, formed by long scars, as if in the depressions 

 between them something like white powder had been left. 



(5) The grain of the shell in the eggs of the swan-geese (Cygnopsis) is smooth and of a crystalline 



character. It approaches in granulation the shells of Bewick's swan. 



(6) The grain of the shell in the eggs of the group of black-legged geese is exceedingly smooth, with 



hardly perceptible pores. It approaches that of the shells of ducks' eggs. 



I fully recognise that it is impossible to describe more accurately the structure of the shell, for the 

 simple reason that it is difficult to find descriptive terms commonly intelligible ; and I therefore confine 

 myself to these general characters which afford a starting-point in the determination of goose-eggs. If, in 

 doing so, I use expressions of a somewhat unscientific character, I hope I shall not be called to account. 

 So-called scientific descriptions of the structure of the shell (when such are given) have never enabled me to 

 reproduce an even approximate picture of the pattern on the surface of the shell, with the exception of 

 those of old Thienemann, which exist, unfortunately, only in the shape of separate fragments for a few 

 groups of birds. 



As great confusion would have been avoided in the goose-question if later ornithologists had availed 

 themselves of the descriptions of the species in the works of Naumann, which for some reason remained 

 for a long time in complete neglect, so oology would have made great strides and not have still remained 

 in its infancy if ornithologists had made use of the foundation so strongly laid by Thienemann, who, three- 

 quarters of a century ago, divined, in his strictly scientific studies of eggs, that the chief characters for the 

 true determination are included in the structure of the shell, i.e. in its grain and in the weight of the egg, 

 and by no means only in colouring and dimensions. The last character is indeed almost devoid of import- 

 ance, since, notwithstanding its considerable variation, the length of the egg with the diameter constant 

 exerts but very little influence on the weight. 



Unfortunately, a working knowledge of the structure of the grain of the shell is greatly hindered by 



1 In view of the confusion between M. arvensis sibiricus and the large M. segetum serrirostris and, finally, M. mentalis, it is 

 impossible as yet to say anything positive ; but owing to the size of the eggs, and especially the abundance in Siberia of M. arvensis 

 sibiricus, it must be supposed that the eggs in the St. Petersburg Zoological Museum belong to this species.— Author. 



