374 BIRDS OF TUNISIA 



coloiu- olivaceous, with lilac-grey underlying marks, and brown surface- 

 blotches. Their average measurements are 73 x 50 mm. 



As in the case of some other sea-birds in these southern countries, 

 the eggs of this species seem to be left uncovered during a considerable 

 portion of the day, the progress of their incubation being doubtless 

 unarrested owing to the warmth of the sun's rays. 



LARUS FUSCUS, Linnffius. 

 LESSER BLACK-BACKED GULL. 



Larus fuscus, Linn. Sijst. Nat. i, p. 225 (1766) ; Mallicrbe, Faaite Oin. 

 dc I'AUj. p. 35 (1855) ; Koenig, J. f. 0. 1888, p. 289 ; id. J.f. 0. 1893, 

 p. 100 ; Saunders, Cat. Birds Brit. Mus. xxv, p. 250. 



Clupeilarus fuscus, Lochc, Expl. Sci. AUj. Ois. ii, p. 181 (1867). 



Larus f uscescens, Koenig, J. f. 0. 1896, p. 189 ; Erlanger J. f. 0. 1900, 

 p. 75. 



Description. — Adult male, spring, from Tunis, North Tunisia. 



Entire head, neck, mantle, rump, tail and under parts pure white ; back, 

 scapulars, secondaries and upper wing-coverts slate-black, the larger coverts 

 and secondaries tipped with white ; edge of wing white ; outermost primary 

 black, with a white patch towards the tip, the remaining primaries black, 

 slightly tipped with white. 



Iris pale yellow ; bare skin round the eye vermilion ; bill yellow, with 

 a red patch on the edge of the lower mandible ; feet yellow. 



Total length 21 inches, wing 16'50, culmen 2'30, tarsus 2-20. 



Adult female similar to the male. 



Observations. — Apparently this species takes four years to acquire its 

 fully adult plumage. 



The Lesser Black-backed Gull is not uncommon in Tunisia during 

 the winter months and on passage, but does not appear to breed any- 

 where in the Regency. According to Blanc, although usually keeping 

 out at sea, the species may occasionally be observed on the Lake 

 of Tunis, and is to be met with in winter all along the coast. I have 

 obtained examples at Sfax, and Dr. Koenig states that the species 

 is abundant at Gabes, and is to be found also at Tripoli. 



On the coasts of Algeria and Marocco, particularly the latter, this 



