I have elsewhere shown, in the works cited below, that the most satisfactory basis for a phylogenetic classification of the spiders referred by Simon to the A viculariinre is furnished by the stridulating-organs, or rather hairy structures that are found between the base of the mandible and palp or palp and first leg. By their structure, in conjunction with other features, the spiders in question fall into a series of natural groups*, each of which, with the exception of the last, is confined to a definite geographical area.