Toner container

A container for supplying toner includes a containing portion with an opening through which toner is moved into a receiving sump. A cover for the opening is flexible enough to move in an arcuate path from a position coveting the opening to a position of storage alongside a sidewall of the containing portion. The cover is stiff enough to be pushed back to its covering position. The leading edge of the cover in its movement back to its coveting position is made concave to the direction of movement so that it will more easily enter a channel partially defined by a seal around the opening. A protrusion on the cover enters a hole in a cover holding member when the cover is in its coveting position to lock the cover in place when the container is not on a receiving apparatus. The protrusion can be pushed out of the hole, unlocking the cover by an appropriate receiving member.