A NEW CRETACEOUS CRAB, DIAULAX-MILLERAE (CRUSTACEA, DECAPODA), FROM THE NORTHERN ATLANTIC COASTAL-PLAIN, USA

Two specimens representing a new species, Diaulax millerae, of a Cretaceous crab were collected from spoil banks of the Chesapeake and Delaware Canal from the lower Campanian Merchantville Formation. The new species is characterized by a hexagonal, relatively flat carapace with moderately developed grooves and prominent tubercles on the epibranchial dorsal shield margins. The specimens are preserved as internal carapace steinkerns enclosed in apatite concretions associated with numerous decapods of the Chesapeake and Delaware Canal Assemblage. The description of D. millerae extends the stratigraphic range of Diaulax from the Early Cretaceous into the Late Cretaceous. Review of the stratigraphic and geographic distribution of Diaulax shows a possible pattern of development along the northern margin of the Tethys Seaway in Texas followed by an eastern migration into Great Britain during the Early Cretaceous, then immigration into the opening Atlantic during the Late Cretaceous.