Girls, Girls, Girls
Well what more can i say. ERB has the best array of heroine's in any pulp story. He has princesses and cavegirls by the score and not forgetting the lovely Jane.
However does he come from a sexist age, the girls are often eye candy, after all. The red flower has a girlish figure in very little clothing, Deja Thoris is as good as naked and jane is often depicted slipping into something more jungle comfortable.
Well despite all this, his girls still kick arse. Deja is let's face it always captured, but she's a scientist who can hold her own in a fight. The girls of pellucidar may be scantily clad but fight openly with Mastadons and other creatures of the stone age.
So ERB has created a good balance of damsel, intellegence, sexy, strong willed and tough. They may be pictured in many peoples minds as the typical pulp fantasy female (all boobs no brain) but in all honesty they are often well rounded and heroic without losing their softer side