A new genus of theridiid spiders in which the male develops only one palpus

The discovery of the male of Theridion fordum Keyserling, reveals characteristics for that species which set it off as genericallv different, from Theridion proper. The erection of a new genus is thus found necessary for this species; and several other species which are closely related to it naturally follow it in this separation. It is quite apparent that mixtum Cambridge, oblivium Cambridge, passivum Keyserling, and minor n. sp. are congeneric with fordum. Theridion migrans Keyserling probably belongs here also, and possibly morulum Cambridge, rostratum Cambridge, and purum Cambridge.