A small fossil sand crab carapace collected from early Eocene shallow water marine strata of the Crescent Formation exposed at Crescent Bay, Clallam County, Washington State, represents a new genus and species, Sklallamia buchanani. The carapace of S. buchanani is nearly as long as wide, is almost equally convex when viewed anteriorly, posteriorly, or laterally with smooth carapace grooves and a low median ridge, has a narrow front with anterior margins that are broadly convex on either side of the lateral margins of the ocular sinus, with broad, short ocular spines and a broad, short rostrum. This is the first confirmed fossil record of the family Albuneidae from the Pacific Basin.