I can't figure out how to change the bulb - map reading light 1990 Dodge Caravan

I have a 1990 Dodge Caravan complete with collector plates. I bought new bulbs to replace the burnt out map reading lights, but have no idea how to open the enclosure for the lights. There are no screws and no obvious places to pry open. Does anyone have experience doing this?

If nobody here knows, stop by the local Dodge dealer at a time when they aren’t very busy, and ask someone there. They’ll likely be happy to give you the straight dope.