ANALYTICAL TABLE OF THE HIGHER GROUPS. 
157 
Bill about as long as head, stout, straight, scarcely tapering, strongly hooked. 
Nostrils abortive. Gular sac moderate, but evident; mostly naked. Wings 
short. Tail large, fan-shaped, scansorial, of twelve to fourteen broad stiff feath- 
ers, exposed to the base. Legs inserted far behind centre of equilibrium LI. Graculidce. 
Bill rather longer than head, slender, perfectly straight, tapering to an acute 
tip. Gular sac small. Nostrils minute. Wings and tail, and general configura- 
tion, as in the last LII. Plotidce. 
Bill much longer than head, straight, stout, strongly hooked. Nostrils very small. 
Gular sac well developed. Wings exceedingly long, strong, and pointed. Tail 
exceedingly long, deeply forked. Feet extraordinarily short ; tarsi partly feath- 
ered LIII. Tachypetidce. 
Bill about as long as head, straight, stout, tapering to an acute tip. Nostrils 
small. Gular sac rudimentary, feathered. Wings moderate, pointed. Tail 
short, but with two central feathers extraordinarily prolonged and filamentous. 
Feet small, beneath centre of equilibrium LIV. Phcethontidce. 
Analysis of Families of LONGIPENNES. 
Nostrils not tubular, lateral, perforate. Bill with continuous covering, or only 
broken by a sort of cere, hooked or straight to the end. Hallux small and ele- 
vated, but always present LV. Laridce. 
Nostrils tubular, disjoined and lateral, or oftenest superior and united in one 
double-barrelled tube. Covering of bill in several pieces ; bill always hooked. 
Hallux minute, rudimentary, or absent LVI. Procellariidce. 
Analysis of Families of PYGOPODES. 
Feet four-toed, palmate. Hallux lobate, connected at base with base of inner 
toe. Tail perfect. Head closely and completely feathered. Nostrils with a de- 
pending lobe or flap. Bill straight, compressed, acute . . LVII. Colymbidce. 
Feet four-toed, lobate. Hallux lobate, free. Tail rudimentary. Head with a 
naked loral strip and bristly or variously lengthened feathers. Nostrils simple. 
Bill straight or decurved at end, compressed, acute . . . LVIII. Podicipidce. 
Feet three-toed, palmate. Hallux absent. Tail perfect. Head closely feathered 
or variously crested. Nostrils simple. Bill of indeterminate shape . LIX. Alcidce. 
' .U : 
