A collection of Cretaceous and Eocene specimens of decapod crustaceans from southern Vancouver Island, British Columbia, Canada, has yielded the following new taxa: Cowichianassa meckerti, new genus, new species (Callianassidae); Comoxianassa haggarti, new genus, new species (Callianassidae); Preclarocarcinus parvus, new genus, new species (Homolodromiidae); and Nitotacarcinus canadensis, new species (Tumidocarcinidae). Two of the new taxa are callianassid ghost shrimp, each of which displays sexual dimorphism and is well documented from major and minor claws as well as abdomina, unusual in the fossil record and especially unusual for Cretaceous forms. Nitotacarcinus was known previously only from the Eocene of Denmark; thus, the new species extends its paleobiogeographic range dramatically. The layers in which the decapods were collected from the Paleogene Via Appia Beds were deposited in generally high-energy conditions favoring the formation of glauconite. Cuticular structures of Eucorystes platys Schweitzer and Feldmann, 2001, are described.