A DISSERTATION SUBMITTED TO THE FACULTY OF SClENCE, UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG, FOR THE DEGREE OF DOCTOR OF PHILOSOPHY. / An assemblage of Cretaceous, Diptera, recovered from the sediments of the Orapa Diamond mine, Botswana, is described. The fossil Diptera are placed In the following families: Tipulidae, Empididae, Hybotidae, Bibionidae, and possibly the Mycetophilidae, Rhagionidae and Anisopodidae. A new pulid species, Helius botswanensis (Tipulidae, subfamily Limoniinae), is described; it is the oldest representative of the subfamily. (Abbreviation abstract) / Andrew Chakane 2019