As you enter the bat caverns you'll notice Mara script around the cavern opening. It is missing some words where the opening seems to have been blasted in. What can be seen reads (underlined is what might be missing):
BEWARE THE DEADLY BOOBY TRAPS
THAT LIE BEYOND THE HIDDEN
PASSAGE RABID BATS
POISON LEAD
TO DEATH ETERNAL DOOM
MARA WEALTH
EVIL SHOULD QUIT
AS EYE
KILL TO JAMMED
SPIKES DESIRE
YOU VIRTUE