and 10 the shelf is ready to be installed in the lugs 5 6 to achieve this the rear edge 11 of the shelf is inserted into the hollow of holder 7 causing the cams 29 to contact the lugs 5 6 and force the wings 23 inwardly the shelf is provided with slots 35 facing the wings 23 to accommodate the inward displacement of the wings when the outer projecting portions 28 of the studs 25 reach the blind bores 26 in the lugs 5 6 the projecting portions 28 snap into the blind bores and secure the shelf in the lugs the tab locks 30 are then slidably moved rearwardly until outwardly facing flanges 36 of the tab locks bear against the frame 8 of the holder 7 as seen in fig1 and 13 the locking teeth 34 on tongues 33 are now engaged with the ratchets 32 and the shelf is tightly secured to the lugs the canisters 1 2 are now ready to be secured to the shelf 4 to complete the assembly as will be explained hereafter fig1 is an exploded view of the dry paper canister 3 which includes a semi cylindrical cover 40 of dome shape and a flat base 41 on which the cover 40 is formed the canister 3 is preferably made of thin plastic material which can be injection molded dry paper not shown is interleaved or otherwise connected and placed in the canister so that the paper can be extracted either as.