This volume provides a comprehensive, highly detailed topographical description of the entire tail apparatus of the pigeon including a functional analysis of the movements of the entire tail and its appendages, namely the flight feathers. The manner in which the flight feathers are incorporated into the uropygium has never before been so carefully studied. Foremost among the features of the tail described here for the first time is the bulb of the rectrices. The topographic relationships of the bulb, its external and internal architecture, the attachments and arrangements of its flight feathers, and its socket are described. Also included are accounts of the components of the tail, its skeleton, joints, intrinsic and extrinsic musculature, vasculature, and innervation. There is an analysis of the movements of the entire tail and its various elements, as well as a discussion of the topographic and functional relationships of the tail and cloaca, of the neural control of the tail and of its functions in flight, braking and balance. A preliminary comparative survey of the tail apparatus in representatives of several avian orders has been made. Finally, the unexpected influence of the tail apparatus in visceral functions such as defecation, respiration and vocalization is considered.