1905.] HYBRIDS AMONG NORWEGIAN BIRDS. 21 



B. Winter specimens (December to April) have as a rule 

 contained food similar to that found in the ptarmigan. It 

 seems, as a rule, that the food has come from rather damp 

 country, and it consisted principally of tiny stalks of various 

 willows, of Vaccinia, and to some extent of dried berries and 

 leaves. 



The recognisable parts of the willows have generally be- 

 longed to Salix lappomim and S. glauca; those of the Vac- 

 cinia were the cowberry (V. vitis-idaea), with its stalks, berries 

 and leaves, stalks of bilberry ( V. myrtillus), and dried or frozen 

 berries of Oxycoccus and Empetrum; further, catkins of the 

 mountain birch, tips of heather (Calluna) and of certain grasses 

 and sedges (Carex, sp.), twigs of juniper with their berries (and 

 cecidomyian formations), and leaves of Arctostaphylos alpina. 



A specimen shot in Rånen on the 18 th January, 1898, after 

 partaking of a good meal, contained the following food : 



In its crop, two handfuls of fragments of leaves and stalks 

 of the cowberry (Vaccinium vitis-idaea), some «catkins and twigs 

 of the mountain birch (Betula odorata, alpigena), and buds and 

 tiny stalks of Salix lapponum. The stomach contained half- 

 digested parts of the above articles of food, and coarse gravel. 



The gravel that is found in many, though not in all, sto- 

 machs, mixed with the food, generally consists of small, similar- 

 sized, rounded pieces of quartz, as large as a good-sized hemp- 

 seed, and almost always white in colour or transparent. . 



The Generative Organs have hitherto been examined only 

 in winter specimens, where they have as a rule proved to be 

 comparatively well developed. The testes are of a greyish brown 

 or blackish colour; and the left one, of which the length has 

 been up to 7 mm , is always larger than the right (length 5 mm ), 

 which generally lies a little higher than the left. In other spe- 

 cimens, the testes may be somewhat smaller, the right one 

 occasionally being quite rudimentary. 



In the female, only the left ovary is present, and that is 

 only poorly developed. 



