THE OLDEST AIR-BREATHERS 2/9 



have left no trace of their existence. On a surface of similar 

 character, sixty feet higher, and separated by three coals, with 

 their accompaniments, and a very thick compact sandstone, I 

 observed a series of footprints, which may be those of Dendrer- 

 peton or Hylonomus. 



SPECIES OF MICROSAURIA. HYLONOMUS LYELLI. 



In the original reptiliferous tree discovered by Sir C. Lyell 

 and the writer, at the Joggins, in 1851, there were, beside the 

 bones of Dendrerpeton Acadianum, some small elongated 

 vertebrae, evidently of a different species. These were first 

 detected by Prof. Wyman, in his examination of these speci- 

 mens, and were figured, but not named, in the original notice 

 of the specimens. 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 speci- 

 mens, was induced to refer them to three species, all appa- 

 rently 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 illustra- 

 tions of the teeth and other characteristic parts. x 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 a 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. ariedentatus. This I had subsequently to remove 

 to a new genus, Smilerpeton. 



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

 about an inch in length, and its whole body, including the tail, 

 could not have been more than six or seven inches, long. The 

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



1 Journal of Geological Society, vol. xvi. 

 14* 



