Here are some more of John R. Neill's early color endpaper designs, used by Reilly & Britton on books by L. Frank Baum. It's a shame that the color endpapers were dropped after Tik-Tok of Oz (1914), as the bright images really do whet your appetite for the story to follow.
For John Dough and the Cherub (1906) and Ozma of Oz (1907), Neill used a similar format in his endpaper designs. Both have the same red and black stripes at top and bottom, containing the action-packed image. In the Ozma drawing, we have a typical case of Neill creating a fun image that has nothing to do with the actual story - I'd be very surprised to find the Nome King intermingling so easily with the other Oz characters! John Dough also features a scene not found in the actual story - although the idea of the Mifkits trying to exact some revenge on Para Bruin, the rubber bear, isn't too far-fetched!
There is a similar stripe again in the design for Sky Island (1912). I'm showing this paired with its companion volume, The Sea Fairies (1911). The Sea Fairies has a very different look than most of the other color endpapers by Neill. Rather than the fine pen & ink style generally seen, this drawing has the rougher appearance of graphite or conte crayon on textured paper - a very different look, but one that Neill used frequently in other artwork.
Another unusual combination is seen in the original endpapers for The Marvelous Land of Oz (1904). Neill's drawing was combined with a photo of Fred Stone and David Montgomery in their respective roles as the Scarecrow and Tin Woodman from the stage production of The Wizard of Oz. As this second Oz title was written with both eyes on the stage possibilities, this seems like an appropriate tie-in. But contemporary readers might be a little confused - it's not Ray Bolger and Jack Haley!