GREAT BLACK-BACKED GULL. 315 



voice when I call aloud ' Gull, Gull ;' for whether he be on wing or 

 afloat, he immediately approaches me. 



" A few pairs of the Great Black-backed Gull breed at the Bass Rock 

 yearly, and it seems highly probable that my specimen had originally 

 been hatched there. If I may be allowed a conjecture, I would suppose 

 that, after attaining maturity, he for some years resorted to the same 

 spot for the purpose of breeding ; but that of late years, having lost his 

 mate or encountered some other disaster, he has extended his migration 

 for that purpose to some very distant locality, which has rendered his re- 

 turn to winter quarters six weeks later than formerly." 



Lahds mauinus, Linn. Syst. Nat. vol. i. p. 225 — Lath, liid. Omith. vol. ii. p. 813. — 



Ch. Bonaparte, Synopsis of Birds of the United States, p. 362. 

 Black-backed Gull, or Cobb, Nuttall, Manual, voL ii. p. 308. 



Adult Male in Summer. Plate CCXLI. 



Bill shorter than the head, robust, compressed, higher near the end 

 than at the base. Upper mandible with the dorsal line nearly straight at 

 the base, declinate and arched towards the end, the ridge convex, the 

 sides slightly convex, the edges sharp, inflected, arcuate-declinate towards 

 the end, the tip rather obtuse. Nasal groove rather long and narrow ; 

 nostril in its fore part, lateral, longitudinal, linear, wider anteriorly, per- 

 vious. Lower mandible with the angle long and narrow, the outline of 

 the crura rather concave, as is that of the remaining part of the mandible, 

 a prominent angle being formed at their meeting, the sides nearly flat, 

 the edges sharp and inflected. 



Head rather large, oblong, narrowed anteriorly. Neck of moderate 

 length, strong. Body full. Wings long. Feet of moderate length, ra- 

 ther slender ; tibia bare below ; tarsus somewhat compressed, covered an- 

 teriorly with numerous scutella, laterally with angular scales, behind with 

 numerous small oblong scales ; hind toe very small and elevated, the fore 

 toes of moderate length, rather slender, the fourth longer than the second, 

 the third longest, all scutellate above, and connected by reticulated en- 

 tire membranes, the lateral toes margined externally with a narrow mem- 

 brane. Claws small, slightly arched, depressed, rounded, that of middle 

 toe with an expanded inner margin. 



The plumage in general is close, full, elastic, very soft and blended, 

 on the back rather compact. Wings very long, broad, acute, the first 



