Edgar Rice Burroughs 
Escape on Venus 
Venus Book 4

When Carson Napier, astronaut from Earth, attempted to help Duare, princess of Vepaja, find her homeland on an unmapped cloud-shrouded planet, they found more trouble than they had ever desired.They found it in Mypos, the country of amphibian people; in the land of the Brokols, whose young grow on trees; and in Voo-ad, the city of the human amoebae. How they escape from their strange predicaments is a thrill-a-page novel of Venus by the author of the famous Tarzan novels.