The species enumerated in this paper belong to the two orders Phillopoda and Decapoda.

Of the Phyllopods, the author describes two species of Ceratiocaris (Salter), which differ from their Upper Silurian allies in the enormously-developed abdomen and in the small size of the carapace, also in the comparative insignificance of the side spines of the tail compared with the telson. As far as the author is aware, these are the first obtained from the Calciferous Sandstone series, although carapaces of Ceratiocaris have been got from the Mountain Limestone of England. (C. Scorpioides, 1½ to 2 inches long; C. elongatus, 5 to 8 inches long.)