Primates are avid explorers that utilize a variety of sensory clues from the environment. The special senses of olfaction, audition, and particu­ larly vision are thus of paramount significance in the evolution and adaptive radiation of the primates. It was with this in mind that this volume was planned to present some recent research advances. The chapter on olfactory communication among primates affords new insights concerning a sense which, though primatologists have generally relegated it to a minor role, is of considerable significance in the primates. The chapters on the auditory system are organized to stress three aspects: the receptive organ, the neural pathways, and the role of audition in primate communication. The visual system, the dominant special sense of primates, is analyzed with respect to two regions of the brain, namely, the organization of the superior colliculus and the visual cortex. Finally, the chapter on endocasts in the study of primate brain evolution will alert neurobiologists to the relevant information that can be unearthed from fossils embedded in the terrane. I wish to thank the publishers, and especially Miss Phyllis Straw and Mr. Seymour Weingarten, for their support, patience, guidance, and professional assistance.