Entropy and much else haunts New York’s rapid transit system, one of the oldest in the world. The subway is fertile grounds for fear: the rats, the tons of dirt above your head, and the leaks you hope are water. And when you get home, you may find that bedbugs got off at your stop. Inspired, Andrew Duncan Farmer has written a collection of “Scary Stories to Read on the Subway,” with illustrations by Bats Langley.