Praise be for the IMDb! I've been trying for years to remember the name of this series correctly, and some other user mentioned it in his memories of _The Man Who Had to Sing_, one of the shorts from this remarkable series. I was already a fan of animation, but I had become aware of non-US films only a few years before the International Festival began to air. Suddenly I was catapulted into the many films of the NFB, of Zagreb Films, of the UK producers, and so forth. The material was so rich, varied, and surprising that missing a single airing was never an option in our household! As the above-mentioned user noted, I still sing the poor little man's "ya, ya, ya, ya-ya" song decades later. I still remember the one-minute adventures of Maxi Cat and fall into fits of snickering. I still, at least once a year, try to learn the name and authorship of that amazing line-drawing animation that traces the rise of "civilization" since the demise of the dinosaurs--a marvelous ending that one has, that I'd never dream of revealing here even with a spoiler alert! When one hasn't seen a snippet of works in some 20 years, then such recollection really says something about quality.
I once wrote to PBS (getting the words in the series name out of order), asking if this wonderful series was available or ever would be, and the person who answered had no idea what I was talking about.