6 ARKIV FÖR ZOOLOGI. BAND 12. N:0 7. 



white apical spöts, the two following black, transverse bands 

 inside the white, apical spöts. The fifth (ef. the note) and 

 following primaries are bluish grey with white tips and with 

 no trace of transverse, dark subapical bars. 



The hybrid specimen lately received shows the following 

 pattern (fig. 3). The first primary is black on the outer web nearly 

 to the base, and on the inner web for about half the length, 

 the remaining part being grey. The tip is occupied by a 

 great white »mirror» extending över both webs and with a 



i^ig. 3. Diagram oi primaries of an adult Larus fuscus ef X L. leucopteru8 $ . 



maximum length of 57 mm. Outside this there is on the 

 extreme tip a small, black spöt which in its present worn 

 state is only 4 mm. The second primary is black on the outer 

 web for about half the length of the quill. On the inner 

 web the gvey »wedge» begins not quite 9 cm from the tip, 

 but next to the shaft the black is continued for about 6 Va 

 cm further proximally. A great white mirror extends across 

 both webs for 32 mm measured along the shaft. On the 

 outer web it has probably extended somewhat further distally, 

 although this is worn off. The black tip outside the »mir- 

 ror» measures 16 mm (on the inner web). The extreme apical. 



