THE OLDEST AIR-BREATHERS 283 



elaborately ornamented and protected as any of the modern 

 lizards, and this, let it be observed, constitutes another and im- 

 portant departure from that batrachian type to which these 

 animals are supposed to conform. I may add here that sub- 

 sequently portions of skin were found, which from their size 

 probably belonged to Dendrerpeton, and that these also were 

 scaly and had lappets, though they did not appear to have the 

 horny tubercles and fringes. It may be asked why such 

 advanced characters should be found in Nova Scotia alone. 

 The answer is that the circumstances of preservation in the 

 erect trees were peculiar, and that only animals of purely ter- 

 restrial habits could find access to them, whereas the remains 

 of reptiles found in the Carboniferous elsewhere are in aqueous 

 beds in which aquatic forms were more likely to be preserved, 

 and in which all the soft parts were certain to perish. 



It is evident from the remains thus described, that we have 

 in Hylonomus Lyelli an animal of lacertian form, with large 

 and stout hind limbs, and somewhat smaller fore limbs, cap- 

 able of walking and running on land ; and though its vertebrae 

 were imperfectly ossified externally, yet the outer walls were 

 sufficiently strong, and their articulation sufficiently firm, to 

 have enabled the creature to erect itself on its hind legs, or to 

 leap. They were certainly proportionately larger and much 

 more firmly knit than those of Dendrerpeton. Further, the 

 ribs were long and much curved, and imply a respiration of a 

 higher character than that of modern Batrachians, and conse- 

 quently a more highly vitalized muscular system. If to these 

 structural points we add the somewhat rounded skull, indicat- 

 ing a large brain, we have before us a creature which, however 

 puzzling in its affinities when anatomically considered, is clearly 

 not to be ranked as low in the scale of creation as modern 

 tailed Batrachians, or even as the frogs and toads. We must 

 add to these also, as important points of difference, the bony 

 scales with which it was armed below, and the ornate appa- 



