70 
VOLITATRICES, 
OEDER II. VOLITATRICES. GLIDERS. 
Birds of small or moderate size, having the body shorty 
and proportionally light ; the neck very short ; the head 
roundish and depressed. Bill very short, of great breadth 
at the base, the mouth being extremely wide ; upper 
mandible with its dorsal line straight until near the end^ 
when it is decurved, the basal sinuses wide, the sides de- 
pressed, the edges arched and continuous, the tip very 
small and deflected ; lower mandible with the angle wide, 
the dorsal line extremely short, and convex, the edges 
arched, the tip very small and pointed. Mouth capacious, 
generally wider than the head ; tongue small, triangular ; 
oesophagus wide, without crop ; proventriculus with a belt 
of oblong glandules ; stomach large and thin, or mode- 
rately muscular ; intestine of moderate length and width ; 
coeca none, or very small, but in the nocturnal species 
large and oblong. Nostrils small ; eyes of moderate size 
or large ; aperture of ear large. F eet extremely small ; 
tarsus very short ; toes four, short ; claws curved, com- 
pressed, acute. Wings very long, generally narrow. 
The V olitatrices have a peculiarly light and bounding 
flight, glide along with surprising speed, deviate on oc- 
casion as if without effort, and seem scarcely liable to 
fatigue on their aerial rambles, which are therefore 
extremely protracted. Owing to the very diminutive 
size of their feet, they are all incapable of walking effi- 
ciently, or of advancing to any distance on the ground or 
on trees. They feed on insects, which they seize in open 
flight, with the bill. Three distinct groups, the Gyp- 
