168 AIR-BREATHERS OF THE COAL PERIOD. 



his examination of these specimens, and were figured, but not named, 

 in the notice of the specimens in the Journal of the Geological 

 Society, Vol. IX. In a subsequent visit to the Joggins, I obtained 

 from another erect stump many additional remains of these smaller 

 reptiles, and, on careful comparison of the specimens, was induced 

 to refer them to three species, all apparently generically allied. 

 I proposed for them the generic name Hylonomus, " forest-dweller." 

 They were described in the proceedings of the Geological Society 

 for 1859, with illustrations of the teeth and other characteristic 

 parts.* The smaller species first described I named H. Wymani] 

 the next in size, that to which this article refers, and which was 

 represented by a larger number of specimens, I adopted as the 

 type of the genus, and dedicated to Sir Charles Lyell. The 

 third and largest, represented only by a few fragments of a single 

 skeleton, was named H. aciedentatus. 



Hylonomus Lyelli was an animal of small size. Its skull is about 

 an inch in length, and its whole body, even if, as was likely, fur- 

 nished with a tail, could not have been more than six or seven 

 inches long. No complete example of its skull has been found. 

 The bones appear to have been thin and easily separable ; and 

 even when they remain together, are so much crushed as to render 

 the shape of the skull not easily discernible. They are smooth on 

 the outer surface to the naked eye ; and under a lens show only 

 delicate uneven striae and minute dots. They are more dense and 

 hard than those of Dendrerpeton, and the bone-cells are more 

 elongated in form. The bones of the snout would seem to have been 

 somewhat elongated and narrow. A specimen in my possession 

 shows the parietal and occipital bones, or the greater part 

 of them, united and retaining their form. We learn from them 

 that the brain-case was rounded, and that there was a parietal 

 foramen. There would seem also to have been two occipital 

 condyles ; (see plate V, fig. 8.). Several well preserved specimens 

 of the maxillary and mandibular bones have been obtained. They 

 are smooth, or nearly so, like those of the skull, and are furnished 

 with numerous sharp, conical, teeth, anehylosed to the jaw, in a 

 partial groove formed by the outer ridge of the bone. In the an- 

 terior part of the lower jaw there is a group of teeth larger than 

 the others. The intermaxillary bone has not been observed. 

 (Figs. 1, 2, 3, 4, 5, 6.) The total number of teeth in each ramus 



* Journal of Geological Society, Vol. XVI. 



