Pseudomma heardi n. sp. is described and illustrated. Specimens were obtained from plankton samples taken in 18 to 60 meters depth in offshore waters of Mississippi. This new species can be distinguished from other species of Pseudomma by the presence of 16 to 21 serrations on the anterior and lateral margins of the ocular plate, strong lateral spine of antennal scale which extends well beyond apex of scale and 4 to 6 spines on lateral margins of telson