According to a letter from Bill Harris in Robin Snyder's The Comics Vol 23, No 8, August 2012, he wrote all the Phantom stories.
In the original story it's Bengali, not Denkali.
Ancient jungle saying 'When the Phantom speaks the whole jungle listens!'
Both pages have '(c) King Features Syndicate, Inc. 1965. World rights reserved.'
Indicia at the bottom of the page.