MG Midget Sprite charcoal cannister question

[stinkyonion]

I have a Lotus Elise.  I had to get rid of its largish charcoal cannister to make room for other modifications.  I bought a MG midget ah sprite charcoal canister on ebay that is one third the size that I will replace the stock canister with.  Problem is, dunno which ports go to where.  One should go to atmoshper, one to tank, and one to carburator.  but which is which??

the canister is round.  there is one port in the center of the top.  there are 2 ports on the perimeter of the top that are connected by tubing.  The third port is on the bottom. 

Anyone know which goes where ?

(cant figure out how to add photo)