When Dr. Katherine Tansley’s Vision in Vertebrates appeared in 1965, it filled a real void that had hitherto existed. It did so by serving at once as a text-book: for an undergraduate course, a general introduction to the subject for post-graduate students embarking on research on some aspect of vision, and the interested non-specialists. Gordon Walls’ The Vertebrate Eye and It. s Adaptive Radiation and A. Rochon-Duvigneaud’s Les Yeux et la Vision des Vertebres have served as important sources of information on the subject and continue to do so even though it is 40 years since they appeared. However, they are essentially specialised reference works and are not easily accessible to boot. The genius of Katherine Tansley was to present in a succinct (132 pages) and lucid way a clear and an interesting survey of the matter. Everyone liked it, particularly the students because one could read it quickly and understand it. Thus, when it seemed that a new edition was desirable, especially in view of the enormous strides made and the vast literature that had accumulated in the past 20 years, one of us (MAA) asked Dr. Tansley if she would undertake the task. Since she is in retirement and her health not in a very satisfactory state both she and her son, John Lythgoe (himself a specialist of vision), asked us to take over the task.