Although the literature on ticks is very extensive, we have failed to find any satisfactory description therein of the process of copulation. Most authors state that the male mouthparts are introduced into the female genital orifice, or vulva, and that this constitutes copulation, leaving it to the reader's imagination to determine how the seminal secretion gains access to the female generative organs. The mechanism of copulation, in other words, remains to be described, and we propose, in this paper, to give an account of what we have observed in Ornithodorus moubata. We shall describe the process in Ixodidae in a later paper, but may state here that, as far as our knowledge goes, it is essentially the same as in moubata, that is, impregnation takes place by means of spermatophores.