It is rarely the ease that we find complete individuals of any species of Lichas, especially in the Ordovician rocks, but several entire specimens belonging to a new British species have been recently collected by Mr. V. II. Turnbull from the Dufton Shales near Melmerby, and detached head shields, pygidia, and hypostomes from the same locality and horizon are not uncommon. Since most species of Lichas have been founded on detached and isolated portions of the body, it is desirable to give a somewhat full description of this new form, which belongs to a group of the genus not previously recognised with certainty in the British Isles.