Chrysopelea paradisi : The Flying Snake

Chrysopelea paradisi is a species of snake found in Asia. It can glide by stretching the body into a flattened strip using its ribs. It is mostly found in moist forests and can cover a horizontal distance of about 100 metres in a glide from the top of a tree.

In 2002, Professor Jake Socha found that the snake uses its ribs to change its body shape; it flattens from head to vent. The snake takes control of its flight by undulating through the air in a distinctive S-shape as if swimming--moving the tail up and down and side-to-side.

Most flying snakes grow 3 to 4 feet long and live in the trees in the lowland tropical rainforests of South and Southeast Asia. Their temperament varies from species to species, and from individual to individual, but all five species of flying snakes are in the Colubridae family and officially are classified as harmless.

Other amphibians and reptiles, as "flying" frogs or "flying" lizards, use the same gliding tecnique. Extra folds of skin enable them to extend their bodies and hold it stiff so that air caught underneath holds them up for a while. As you can see in the next video, the king of gliding flight is the flying dracko (upto 200 metres), followed by flying snakes (150 metres), flying geckos (100 metres) and frogs (80 metres):

More info and sources: 1, 2, 3, 4, 5