This was a 32 part series which occupied the back page of (an otherwise pretty dull) Finding Out magazine in the mid 60s between issues from volumes 15 through to18.
The paintings of the different beasts were painted by the late, great Angus McBride and really blew me away back in the late 70's when I found them in a cupboard at primary school. Some were humourus, some horrific but all of them were absolutely striking. favourites being Mermaids, the Midgard Serpent and the Thunderbird.
I'm now pushing 40, and after a number of years have sourced all issues (mainly from ebay) and even own four of the original Angus McBride paintings.
Those beasts were (in order) as follows: Dragons, Unicorns, Mermaids, Gryphons, Sea Serpents, The Phoenix, Harpies, Satyrs, Nymphs, The Wild Hunt, Hippocamps, Bunyips, Tokoloshes, Maero, White Buffalo, The Cailleach-Bheur, Midgard Serpent, Morrigan, Werewolves, Thunderbird, centaurs, Gnomes, Little People, Lamassu, Cyclopes, Paul Bunyan and Babe, Chinese Dragons, Minator, Huitzilopochtli, Amenit, The Leshy, Domovoi, Poleviks and the Tarasque.