tongue style sewn not just to the vamp, but also all or partway up the insides of the quarters, under the {{facings}, often perforated by the eyelets and any lace hooks
Bellows tongues can prevent water from seeping into a shoe past the lacing and provide additional padding over the insteps.
As with slip-on shoes, a bellows tongue must open wide enough to allow the foot to pass in and out of the shoe.