274 AIR-BREATHERS OF THE COAL PERIOD. 



teeth manifest at least as close a resemblance to those of Gano- 

 cepJiala as of Lacertia or any higher group of Reptilia ; whilst 

 their mode of implantation, with the structure and sculpturing of 

 the bone, weigh in favour of its relations to the lower and earlier 

 order of the cold-blooded Vertebrates." 



I can add to the above description only a few facts obtained 

 from careful examination of other fragments imbedded in the ma- 

 trix. One of these is a portion of a maxillary bone (Fig. 32). 

 It has teeth similar to those of the lower jaw in form (Figs. 34 

 and 35), but the last but one is twice the size of the others, and 

 seems to have been implanted in a deep socket. All of the teeth 

 have large pulp cavities, and the inner surface of the ivory is 

 marked with slight furrows which are represented by ridges on 

 the outer surface of the stony matter filling the pulp cavities 

 (Fig. 36). The ivory of the teeth, however, which is very much 

 coarser than that of the species of Hylonomus, presents in the 

 cross section a simple structure of radiating tubes (Fig. 37). The 

 surface of the cranial bones, of which some fragments remain, is 

 marked in the same striate manner alluded to above by Prof. 

 Owen (Figs. 42, 43). The microscopic structure of the bone is 

 muca coarser than that of Hylonomus or Dendrerpeton, the cells 

 being larger and in some portions less elongated (Fig. 46). That 

 the creature had stout ribs is shown by the fragments represented 

 in Fig. 40 ; but the vertebrae are represented only by a few 

 bodies of small relative size and perhaps caudal (Figs. 38 and 39). 

 On the saune surface was found the foot represented in Fig. 44. 

 It is of small size relatively to the head, and was probably for swim- 

 ing rather than walking. A. few ovate bony scales were found 

 with the bones, and probably belonged to this species (Fig. 41). 



On the whole it seems certain that Hylerpeton must have been 

 generically distinct from the other reptiles found with it, and it is 

 probable that it was of more aquatic habits, swimming rather than 

 walking ; and feeding principally on fish. More perfect speci- 

 mens would however be required in order to warrant any decided 

 statement on these subjects. It is possible, as suggested by Prof. 

 Owen, that the affinities of the animal may be with Archegosau- 

 rus rather than with any of the other coal reptiles ; but I confess 

 that my present impression is that it tends rather toward the 

 genus Hylonomus. It may possibly be a link of connection be- 

 tween the Microsomia and the Archegosauria. 



