The present volume consists of four chapters. The first (by Ollis and Ramsden) classifies and discusses the chemistry of that interesting group of compounds known as meso-ionic heterocycles and includes a useful general definition of the term. The second chapter (Litvinov and Gol'dfarb) deals with systems with two (or more) thiophene (or selenophene) rings directly fused together. The 1,2,3-triazines, along with the better-known 1,2,3-benzotri-azines and other fused 1,2,3-triazine systems, are discussed in the third chapter, by Kobylecki and McKillop. In the last chapter George, Khetan, and Gupta treat heterocyclic syntheses which involve the addition of nucleo-philic reagents to acetylenic esters.