Note:

• Per Wikipedia: -- Published posthumously (Lofting died 1947) -- longest in the series and darkest in tone; "for the first time acknowledges 'nature red in tooth and claw' "; almost misanthropic with comedy "a mere sprinkling"
• Published 15 years after the preceding novel, Doctor Dolittle Returns
• Frederick Abbott Stokes of New York, the publisher of all previous Dolittle books, had died in 1939. Many people from the New York City books industry attended his funeral service, including the Loftings. --Wikipedia "Frederick A. Stokes"; NY Times 1939-11-19 p38 Lippincott of Philadelphia had acquired the Frederick A. Stokes Company in 1943. It published The Secret Lake as "A Stokes book". --ISFDB publisher and publication records

Synopsis: Doctor Dolittle rescues Mudface the Giant Turtle, who had been a passenger on Noah's Ark. "Mudface's account of the Flood and its aftermath takes up most of the book." --Wikipedia