As a sequel to my recent paper on new specimens of Dendrerpeton, I have thought it desirable to reproduce by photogravure, for comparison, the type specimen of Hylonomus Lyelli now in the collection of the Geological Society of London. The reproduction (Plate VIII.) is of the natural size, though less distinct than in the original. Though the bones are scattered, this specimen enabled me, by measuring the separate bones and adding the cuticular scales found on other specimens, to restore the animal in my “Airbreathers of the Coal Period.”