In the year 1881, G. Haller published a description of the sensory organ of ticks which has since borne his name; he was apparently so much impressed by its remarkable similarity in structure to the auditory organs of many Crustacea, that he assumed it to be an organ of hearing, and even went so far as to describe the presence of otoliths within one of the cavities of the organ. Since that time, other zoologists appear to have given little attention to this structure, the majority of those who have had occasion to mention it, contenting themselves with a brief resumé of Haller's observations and a reference to his paper.