Synopsis Coelenterata was formerly regarded as Phylum divided into two subphyla: Subphylum Cnidaria and Subphylum Acnidaria. The name Coelenterata has been derived from two Greek words, Koilos = hollow, enteron = intestine. Thus the name of this phylum literally means hollow intestine but hollow bodies is considered more appropriate because actual intestine is not found in coelenterates. An Introduction to Coelenterata is the revised and enlarged second edition of the book. It has been designed to approach the morphology, anatomy, physiology and development of selected type in a simple and lucid style. According to the scheme of treatment the important animal types of the phylum have been dealt with first, and efforts have been made to present their elaborate and uptodate account. General characters and classification and brief description of other important types of the phylum have also been dealt with complete, authentic and uptodate account. Further separate chapters on topics of significance and general interest pertaining to the phylum have also been added to make the treatment more elaborate.