My guess is they are drawn by Roland Crandall because they look a lot like the drawings and animation in Betty Boop's "Snow White". -but I could be wrong.
I just love this style. When I think of what makes the Fleischers unique it's this kind of look. It's more like the comic strips than what was becoming known as "animation style" in Hollywood.
Some particular animators seem to stand out: Dick Heumer , Grim Natwick, Willard Bowsky, Al Eugster and some others whose styles I recognize but aren't sure of the names that go with them. I like Shamus Culhane's early Fleischer stuff though he disparaged this whole school of animation when we met. So did Myron Waldman.I think this is their best stuff!
They still did some nice animation but I prefer the 30s when they were really doing their own thing. I think Disney made everyone feel guilty for having unique styles and approaches to animation in the 1930s and it led to a general blandification of much of the industry. Luckily some holdouts continued along their own paths: Avery, Clampett, Tashlin, Jones to an extent, Tyer, Scribner, Mckimson, and later UPA.