In a paper published last year, I described the female, nymph and larva of Ixodes caledonicus. Having regard to the views expressed in my recent paper on the adaptation of ticks to the habits of their hosts, I wrote to Mr William Evans, in Edinburgh, asking him, if possible, to kindly search the dove-cot at Dunipace, Stirlingshire, for the missing male which he would probably find in the habitat of the host, the domestic pigeon. On 25 May, 1911, Mr Evans discovered two ticks, a male and female in copula, in the dove-cot, and he sent the specimens to me for identification. The female accords with my published description of caledonicus. The male is here described for the first time, and it is interesting to find that it agrees in structure and habits with what was to be expected according to the theory advanced by me in the second paper I have referred to.