The ostracod fauna of the Gubik Formation comprises 43 species distributed among 29 genera. Four of the genera and 18 of the species are described as new. Nineteen of the species, or roughly 44%, are known to be extant. Both marine and nonmarine species of Ostracoda occur in the Gubik. The marine facies of the Gubik is estimated to extend inland from the present Arctic coast a distance of 10-20 mi or more between Colville River on the E. and Point Bar row on the W.