We regret the error in the Table of Contents of the issue of 18 May. The absence of an Abstracts section is not a defect; there were no Abstracts. As was explained in the Editorial of 17 February, there will be four issues per year without Abstracts; and the issue of 18 May was the second of them. But the force of habit led us to print the usual entry at the end of the Table of Contents anyway! We will try not to make the same mistake again.