Having had our attention directed by Mr. Barkas's paper to the specimens of this genus in the National Collection, and compared Mr. Barkas's figures with Mr. T. Atthey's description of Ctenodus tuberculatus [see “Annals and Magazine of Natural History” (4th series), Feb. 1868 (p. 83)]; Mr. W. Davies having also kindly pointed out to us a small but very perfect palatal tooth (see Plate IX. Fig. 3), probably from the Coal-measures of Carluke (from the collection of the late Mr. Alexander Bryson of Edinburgh), closely agreeing with Mr. Atthey's description in all its characters; we have thought it well deserving of a place in our Plate.