It is indeed a great pleasure to take this opportunity to express a deep sense of gratitude to my Research Supervisor and Guide Dr. A. Jawahar Ali, Reader, Dept of Zoology, The New College, Chennai, for his guidance, inspiration, encouragement in preparing the dissertation throughout its various stages, without whom I would not have completed my course. I am grateful to Principal, Prof. Dr. K. Altaff, The New College for his timely help of my study. I wish to express my special thanks to Prof Dr. M. Arumugam, Head of Dept in Zoology, University of Madras, Chennai, for his timely help and encouragement of my study. I would like to thank my father, mother, brother and my uncle who have rendered moral support and belief in ultimate goals. I wish to express my special thanks to Dr. P. Saravana Bhavan, Reader, Dept of Zoology, Crustacean Biology, Bharathiar University, Coimbatore, INDIA, for his timely help and encouragement throughout the course of my study. I am extremely grateful to my Publication LAP LAMBERT Academic Publishing GERMANY. For their keen interest and kind co-operation in this book. Author N. Manickam