The different species of malaria for which the evidence seems reasonably good have been classified according to their morphological characteristics and their behavior in the canary so that identification is easily possible. In the use of the key which has been included, and the table in which the characteristics of the infections have been tabulated, it must be always remembered that there is much variability even within a given species. It is likely also that the existence of varieties or races within the various species, and even new species, will be demonstrated in the future. The list of references which follows included various papers in which the question of species and their characteristics is discussed, as well as papers cited in the test.
The work on which this paper was based was financed in part by a grant-in-aid from the American Association for the Advancement of Science.