LAND ANIMALS OF THE COAL PERIOD. 371 



tliem to thi'ce species, all apparently generically allied. I proposed 

 for thein the generic name Hylonomus, " forest-dweller." Tliey 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 //. 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. Tlie third and largest, represented only by a 

 few fragments of a single skeleton, was named H. aciedentalus. 



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

 an inch in lengtli, and its whole body, even if, as was likely, furnished 

 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. 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, anchylosed to the jaw, in a partial groove formed by the 

 outer ridge of the bone. In the anterior part of the lower jaw there 

 is a group of teeth larger than the others. The intermaxillary bone 

 has not been observed. The total number of teeth in each ramus of 

 the lower jaw was about forty, and the number in each maxillary bone 

 about thirty. The teeth are perfectly simple, hollow within, and with 

 very fine radiating tubes of ivory. The vertebrae have the bodies 

 cylindrical or hour-glass shaped, covered with a thin, hard, bony plate, 

 and having within a cavity of the form of two cones, attached by the 

 apices. The ribs are long, curved, and at the proximal end have a 

 shoulder and neck. They arc hollow, witli thin hard bony walls. 

 The anterior limb, judging from the fragments procured, seems to 

 have been slender, with long toes, four or ])os.sibly five in number. 

 The posterior limb w^as longer and stronger, and attached to a pelvis 

 * Journal of Geological Society, vol. xvi. 



