During the Late Thirties, with the Production Code bowdlerizing Betty Boop, the Fleischers kept trying to expand their regular series beyond Popeye and Screen Songs. They tried with Wiffle-Piffle, a relative of Termite Terrace's Egghead, but he didn't go anywhere. In 1940 they tried to do a bunch of Prehistoric-themed cartoons, perhaps influenced by reports of Disney's Fantasia. Running to dinosaur-and caveman gags, it was called the 'Stone Age' series. This is the sixth.
It is, as you might guess, a variation of the Ugly Duckling Story. It is rather sentimental for Fleischer, but the gags are numerous and well-constructed, as you might expect for a cartoon directed by Dave Fleischer. The result is a watchable, if not great cartoon.