OF MYTHIC PROPORTIONS:OK, it's a little too late this year, but write this on your calendar for next summer: The museum has summer evening hours. Saturdays until 10, from June through August, enjoy the cooler temps of the intimately lit outdoor corridors that you cruise like a boat down a canal. This is without a doubt the best time to enjoy the outdoor seating at the four dining areas, all open until 9, except for Phoebe's, which is open until 10. And they've got lots of docents creeping around in the dark with blacklights and giving risqué presentations like "Nighttime Pollinators." Be sure to look for your seldom seen nocturnals, such as the mountain lions and beavers, and make a stop by the amphitheater for the hourly sky-gazing demonstration. Sure beats dumping ice cubes into your swamp cooler.