"A Gun for Dinosaur" derives its humor from the contrast between Rivers's casual tone and the suspenseful events he recounts. The story is carefully thought out and told with a slant toward those concerns that would most interest a hunting guide. Rivers, for instance, notes that dinosaur brains are too small to be good targets so he recommends shooting at dinosaur hearts. He is also an analyst of the game animals: "Their weakness is that, having hardly any minds, they have little memories." Thus the best way to escape a dinosaur is to hide behind something; if the beast can neither see nor smell a person he forgets about his prey, even if he or she has just been seen. Out of sight, out of mind is literally true in this case.

One of de Camp's best skills in his long literary career has been the...