My original tumblr post was here, with a comment “Take that, enormous brain.” They were originally posted on Tumblr by Vintage Geek Culture with the comment “‘In the tradition of Edgar Rice Burroughs.’ Oh, most definitely.” I have been unable to discover the name of the artist or artists who created these covers.
The author with three names was very common in the 20s, and is a nice touch here.
Although, Fearn wrote these in the ’50s.
Probably getting his inspiration while growing up in the ’20s.
the hairy ape octopus is a delightful novelty