The primary object of this paper is to inquire into, and bring forward for discussion, those characteristics of the mortality of female lives which belong to their sex as a whole, in the belief that a proper understanding of those characteristics is essential to a correct interpretation of statistics derived from the special class represented by assured lives. To this end an attempt is made, in the earlier part of the paper, to compare the available statistics of assured lives with those of the general population, and some apology perhaps is needed for the space which it has been found necessary to devote to this part of the subject. This, however, is to a great extent unavoidable, and is partly due to the necessity of showing the figures for male lives side by side with those for females, thus involving generally a double set of figures in each table.