Collection of new fossils from the west coast of North America has resulted in additions to the Carpiliidae, Goneplacidae, Panopeidae, and Pilumnidae in the fossil record. Features of the dorsal carapace of members of each of these families, as defined using modern biological classification techniques, are useful in assigning the new fossil taxa to these four families. Description of new taxa and reassignment of several previously described taxa have resulted in a reevaluation of the fossil record of those groups on the west coast of North America. New species include Orbitoplax tuckerae, Panopeus prosakrolophos, and Panopeus torus. New combinations include Branchioplax carmanahensis (Rathbun, 1926), Orbitoplax weaveri (Rathbun, 1926), Panopeus baldwini (Kooser and Orr, 1973), Panopeus olearis (Rathbun, 1926), and Panopeus soledadensis (Rathbun, 1926).