293 



are fed in the nest fof several days; subsequently they run about 

 among the heather, hiding with great dexterity on the approach 

 of danger. When discovered they will scurry off with bill agape, 

 filling the air with their shrill screams, a sight which never fails to 

 exasperate the whole colony wheeling overhead against the pursuer. 



It is almost impossible to distinguish the young of this species 

 from those of L. fusms and marinas at the same stage of growth, 

 the spots on the head and body being distributed in precisely the 

 same manner in each. 



Larus leucopterus, Fab. 



Occurs annually in the winter months on the fjords of West 

 Finmark down to Tromsø. Two individuals (male and female), shot 

 out of a flock which visited Tromsø Sound in December 1870, were 

 transmitted to the University Museum by Pastor Kaurin. 



These two individuals differ very considerably in the mea- 

 surements. 





Wing. 

 • 



Tail. 



Tarsus. 



Middeltoe and 

 Claw. 



Culmen. 



Height of Bill. 



? 



415 



385 



175 

 161 



55 

 51 



48 + 10 

 42 + 9% 



55 

 52 



16V 2 



15 



In the male, the first feather of the primaries is 4 mm longer, 

 and in the female, 4 mm shorter, than the second. 



Male and female in winter dress. Head and breast a good 

 deal mixed with greyish-brown, each feather of these parts having 

 a greyish-brown margin, fainter spots of the same colour appearing 

 on the pectoral plumes near to the shafts. The nape is darkest, 

 being most thickly feathered. Vent and ab domen white, marked 

 with almost obsolete transverse lines, tail white, back and wings 

 light ashy-blue, the tips of the latter being of a somewhat paler 

 shade. The outer web of the first secondaries in the male is faintly 

 sprinkled with greyish-brown, indicating possibly a younger stage. 

 Bill dark horn-brown, excepting the upper edge of the lower 



