GULLS AND ALLIED SPECIES. 475 



dible Avith the ridge convex at the base, narrow beyond the 

 nostrils, which are sub-basal, long, linear, a little wider ante- 

 riorly, margined above with a sloping thin-edged membrane, 

 the edges very thin, inclinate, the tip narrow, rather acute ; 

 lower mandible very much compressed, the lower outline 

 of the crura a little concave anteriorly, forming a slight 

 angle with the dorsal line, which is nearly straight, the edges 

 very thin and inflected, the tip rather acute. Legs of mode- 

 rate length, rather slender ; tibia bare for one-third ; tarsus 

 rather short, compressed, anteriorly covered with numerous 

 curved scutella, laterally Avith angular scales, behind with 

 numerous small rectangular scales ; hind toe very small 

 and elevated ; fore toes of moderate length, slender ; interdi- 

 gital membranes with the margin concave ; claws small, 

 slightly arched, rather acute. Wings very long, rather narroAv, 

 pointed. Tail of moderate length, even or emarginate. 



1. Gavia Atri cilia. Leaden-cjrexj-lwoded Mew. Bill 

 rather stout, an inch and three-fourths long, rich carmine, as 

 are the feet ; outer quills black, the next five with that colour 

 gradually diminishing, their tips Avhite, those of the outer two 

 excepted. In summer the head and part of the neck dark 

 leaden-grey. 



2. Gavia ridihunda. Broivn-hooded Mew. Bill an inch 

 and a third in length, rich carmine, as are the feet ; outer 

 four quills and their coverts white, the first quill Avith the 

 greater part of its outer margin, the tip, and a narrow band 

 along its inner edge, black ; on the next five, no black on the 

 outer web, that on the tip more extended, the black band on 

 the inner edge broader, the tips Avhite, those of the outer two 

 excepted. In summer, the head and part of the neck deep 

 brown, becoming brownish-black behind. 



3. Gavia capi strata. Brown-mashed Meio. Like the last, 

 somewhat less. In summer, a light-brown mask, not extend- 

 ing far beyond the eyes. 



4. Gavia Sahini. Sahine''s Mew. Bill black, at the end 

 yellow, an inch in length ; tarsus an inch and a half ; wings 

 tAvo inches longer than the tail, Avhich is forked. In summer, 

 the head and upper part of the neck all round blackish-grey. 



5. Gavia Bonapartii. Bonaparte'' s Mew. Bill an inch 



