116 BIRDS. PALMIPIDES. 



PALMIPIDES. 



WATER BIRDS. 



I. Hind toe united with the front toes by a continuous membrane. Nasal 

 openings indistinct. 

 Phalacrocorax. 

 Sula. 

 II. Hind toe separate. 



a. Margin of the mandibles with corneous teeth ; the sides of the tongue 

 with tufts of pectinated bristles. 



b. Bill broad. Teeth in the form of transverse plates. 



c. Trachea of the male with a capsular enlargement at the bron- 

 chial extremity. 



d. Hind toe bordered with a membrane^ 



e. Base of the bill enlarged. 

 Oidemia. 

 Somateria. 



ee. Base of the bill plain. 

 Clangula. 

 Nyroca. 



dd. Hind toe not bordered by a membrane. 



e. Bill wide at the extremity. 

 Tadorna. 

 Spathulea. 



ee. Bill nearly of equal breadth throughout. 

 Anas. 



cc. Trachea of the male simple at the bronchial extremity. 

 Cygnus. 

 Anser. 



bb. Bill narrow ; margins with reflected teeth ; the upper mandible 

 hooked at the end. 

 Mergus. 



aa. Margin of the bill and tongue destitute of teeth or bristles. 



b. Wings short. BrachypterjE. 



c. Bill compressed and obliquely furrowed. Tridactyle. 

 Alca. 

 Fratercula. 



cc. Bill conical, subcompressed, and destitute of furrows. 



d. Webs scalloped. A hind toe with a broad web. 

 Podiceps. 



dd. Web entire. 



e. Tridactyle. 

 Colymbus. 



ee. Tetradactyle. 



/. Upper mandible notched at the point. 

 Una. 



ff. Upper mandible plain. 

 Cephus. 

 Mergulus. 



