My Minecraft Adventure Map Won't Show Up In Singleplayer Saves?

I downloaded the Adventure Map: Under The Dome and have been able to successfully install the resource pack to the point where I can select it from the in-game screen. However, the map itself is not showing up in the in-game world select screen. Does anyone have any ideas as what to do?
Added (1). The map is up to date with 1.8.8.

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