• We attributed information about the earthquake-sensitive animals of the city of Helice to the ancient Greek historian Thucydides (17 February, p 34). He is generally thought to have died in 401 BC – about 18 years before the Helice incident. The correct attribution is Diodorus.
• We said that Tangshan, in Hebei province, China, is south of Beijing (17 February, p 36): it is east and slightly south of the capital.
