INTRODUCTION. 
XI 
VI. STEGANOPODES. Hind toe lengthened and incumbered, and united to the inner 
toe by a complete web (small only in Tacliypetidce) . Bill extremely variable, but 
usually with a more or less extensible naked gular sac between the mandibular rami. 
Nostrils obsolete. Habits altricial, young dasypsedic in Tacliypetidce, Phalacrocoracidce, 
Plotidce, and Phaethontidce, gymnoptedic 4 in Pelecanidce and Sulidce. Palate saurogna- 
thous. Carotids double. 
VII. LONGIPENNES. Hind toe small or rudimentary, and elevated, sometimes almost 
obsolete ; anterior toes fully webbed. Bill more or less compressed (nearly cylin- 
drical only in some Stercorariidce ), the nostrils linear, never tubular. Habits altri- 
cial, young dasypaedic. Palate schizognathous. Carotids double. Eggs, two or more, 
colored. 
VII I. TUBINARES. Hind toe absent or very rudimentary ; anterior toes fully webbed. 
Bill variable, but usually nearly cylindrical or compressed (rarely depressed), the ter- 
minal portion strongly hooked. Nostrils tubular. Habits altricial, young dasypaedic. 
Palate schizognathous. Carotids double. Eggs, never more than one, white. 
IX. PYGOPODES. Legs inserted far backward, the tarsi extremely compressed. Anterior 
toes fully webbed or else strongly lobed and with broad flat nails ( Podicipidce ). Bill 
extremely variable. Habits proecocial in Podicipidce and Colymbidce, altricial in Alcidce ; 
young dasypaedic. Palate schizognathous. Carotids double, except in Podicipidce and 
some Alcidce ( e . g., genus Alle). 
The above arrangement is not strictly natural, but the division of Water Birds into “ Waders ” 
and “ Swimmers ” is adopted for the convenience of the student. The Orders most nearly related 
are the Herocliones and Steganopoclcs, Limicolce and Alectorides, Pliamicopteri and Anseres, and Longi- 
penncs and Tubinares. Of the Pygopodes (which as here defined is certainly not a properly 
limited group) the Alcidce present many points of true relationship to the Tubinares and Longi- 
pennes, while the latter are not far removed from the Limicolce. The Podicipidce also appear to 
resemble in some respects (perhaps only teleological) the Steganojjodes. 
1 Young birds are gymnoppedic when naked or very incompletely covered with down when hatched ; 
e. g., the young of all Passeres, Woodpeckers, Pigeons, etc. 
