Abstract
Cunliffe (1921) has shown that the various stages of Ornithodoros moubata may be distinguished by slight differences in the shape of the spiracles. Nuttall, Cooper and Robinson (1908) have described in detail the structure of the spiracles of another tick, Haemaphysalis punctata. Otherwise the spiracles of ticks have received little attention except from systematists, and though Nuttall and his collaborators described a closing mechanism in Haemaphysalis, no study of its function was made. In this paper I propose to describe the structure of the spiracle of Ornithodoros moubata, and show how its function may be investigated by experiments.