This book entitled "An Introduction to Mollusca" is one of the "Phylum series" of invertebrates, deals with the morphology, anatomy, physiology and development of important animals of the phylum. The publication of this books according to the syllabi for the B.Sc. as well as M. Sc. Student of Indian Universities. Many other books published on this phylum is said to include some of Indian types and not all, so every effort is taken to explain almost all the important Indian types. Moreover, the student, what the author feels, sometimes feel difficult to carry and study the large book. So, this book is only contain one phylum, making it handy and has replaced the hardbound books on economic grounds. Efforts have also been taken into consideration to condense the matter as far as practicable. It is hoped that the book will not only meet the requirement of the students but be useful as a guideline to the teachers as well.