The flying squirrels are a tribe of squirrel...

There are 43 species in this tribe, the largest of which is the woolly flying squirrel.
The term "flying" is somewhat of a misnomer, since flying squirrels are actually gliders incapable of true flight.
Gliding is achieved by this animal by launching off the tops of trees and extending flaps of skin stretched from arms to legs: once they have launched themselves into the air they are highly manuverable while in flight.
Steering is accomplished by adjusting tautness of the patagium, largely controlled by a small cartilaginous wrist bone.
The tail acts as a stabilizer in flight, much like the tail of a kite, and as an adjunct aerofoil when "braking" prior to landing on a tree trunk...