I undertook this description of certain fossils from the Lower Palaeozoic rocks ofYorkshire at the request of Mr. Marr. The late Mr. Thomas Roberts had begun the piece of work, but left it unfinished. Nearly all the fossils referred to were collected by a party of Cambridge geologists, under the guidance of Prof. Hughes, in the Summer of 1889. The fossils come from two horizons, viz.:—

1. The Phacops elegans zone≍Stockdale Shale series (Valentian) of Wharfe.

2. The Bala beds≍:Coniston Limestone series of Norber Brow and Wharfe.