De Camp is American, but the voice of his protagonist in this story is delightfully Titanic Era British. Likewise his his description of South African parks and peoples is fun and comes across as authentic. The Okavango River Delta he talks about is real, but so remote and obscure that I had to look it up. (This is also another early work, 1939.)
A nice description of messing around in an insect-infested swamp. This place is apparently a cross between the Great Basin and the Everglades. He misses one point as Cuff gets lost wandering the swamp in the dead of moonless night: Cuff doesn't try yelling to find Mtengeni, the warden. It's a small point.
A little bigger inconsistency is that it took dawn's light for Cuff to recognize that Ingwamza was a baboon, not a human. In starlight a person can tell the difference between a human, a dog, and a cow. At its latest this revelation should have come about slowly as they were sitting and he was watching her motions and listening to her breathing and talking.
And a trope comes up. It turns out Ingwamza is a daughter of the village headman, so Cuff is honored for his rescue and becomes an honored guest of the village. One plot device is revealed: Cuff had accidentally shot himself in the foot so he's mildly wounded and will stay in the village a while to recover.
Wow... this is a 1939 piece and De Camp is talking about genes! And a machine that will mutate them. And he has radiation doing the mutating... although he's real fuzzy on how. This much understanding seems real early. Yes, this is way post-Darwin (1859), but still... as the Robots Return piece previous to this one showed, even the term virus was not yet common. The linking of DNA to heredity would happen starting in 1943 and be confirmed in 1952. Camp was up on the frontiers of biology as well as the frontiers of South Africa.
LoL! He's having fun with the "different strokes for different folks" in what these baboons serve him for food as he recovers. ...And culture! Ingwamza is now ordained to become his wife. ...Yup, he's having fun with culture shock. The inconsistent part here is that these mutated baboons have become human enough to handle mating and community relations in human ways, such as woman sleeping with her man and presumably having sex with him even outside of mating season. Still, it's fun reading.
More trope, a jealous male rival. I checked. Baboons mate annually or biannually, and males are solo types except during mating season, so this rival-and-marriage business is pure anthropomorphizing plot device. But then more fun, a mutated domesticated crocodile that can be a horse. Yay!
All-in-all it's entertaining and well written. De Camp is right up there with Asimov and Heinlein as an imaginative story teller.