The genus Ischnopsyllus Westwood, comprising at the moment sixteen species and subspecies, is rather a heterogenous group. Although I am reluctant to split this relatively small genus, a certain degree of division is unavoidable. First, I. grahami Waterston certainly does not belong to the genus Ischnopsyllus, and since this species does not fit any other genus of bat-fleas, a new genus has had to be erected for it (see below, where a new subspecies of grahami is also described). Secondly, the hexactenus-group of Ischnopsyllus is sufficiently distinct from the rest of the genus to make it desirable to restore, as a subgenus, the genus Hexactenopsylla Oudemans, which was synonymized with Ischnopsyllus by Dalla Torre in 1924.