I believe these blocks were from an early set made by Milton Bradley, late 19th century, which came in a wooden box labeled "Alphabet and Kindergarten Building Blocks." (Milton Bradley was an early producer of Kindergarten materials, including early Froebel Kindergarten blocks.) They are rare ones, and while this is not a complete alphabet, and there are dupes of D,Q, and W, I think they're super beautiful. Letters on one side, animals on the other, litho over paint, with gorgeous color and a wonderful range of animals represented! Xiphias!
Each block measures 2 1/2” x 1 1/4” x 5/8”. Wear as evident. Color richer and black bolder in person.