380 



THE CARBONIFEROUS SYSTEM. 



Hylerpeton Dawsoni, Owen. 



In the more or less laminated material which fills the interior oi 

 the erect trees of the Joggins, it often happens that the more distinctly 

 separable sm'faces are stained with ferruginous or coaly matter, or 

 with fine clay, so that the fossils which occur on these surfaces, and 

 which would otherwise be more available than those in more compact 

 material, are rendered so obscure as readily to escape observation. 

 This was unfortunately the case with one of the most interesting 

 specimens contained in the last of these trees which I had an oppor- 

 tunity to examine. It consisted of the detached bones of a reptile 

 scattered over a surface so blurred and stained that they escaped my 

 notice until most of them were lost ; and I was able to secui'e only a 

 jaw bone and fragments of the skull, with a few of the other bones. 

 On these fragments Professor Owen founded the genus Hylerpeton 

 and the species )iamed at the head of this article. His description is 

 as follows (Fig. 147) : — 



Fig. 147. Hylerpeton Daiosonii Owen. 



(a) Mandible and portion of cranial bone; nat. size. 



(6) Fragment of maxilla, showing larger and smaller teeth. 



(c) Tooth enlarged, showing pulp cavity. 



{d) Section of tooth ; magnified. 



" This specimen consists of the left ramus of a lower jaw, which 

 has been dislocated from the crushed head, of which the fore end of 

 the left premaxillary is preserved, terminating near the middle of the 

 series of the teeth of the more advanced mandible. A fragment of 

 the left maxillary, which has been separated from the premaxillary, 

 overlaps the hinder mandibular teeth. The fore part of the mandible 

 is wanting. The teeth in the remaining part are larger and fewer, 

 in proportion to the jawbone, than in Hylonomus or Dendrerpeton. 



