162 AIR-BREATHERS OF THE COAL PERIOD. 



seen that these teeth differ very markedly in their proportions 

 and form from those of the larger species represented in PI. Ill) : 

 (3) The greater plication of the ivory in the intermaxillary teeth » 

 Figs. 8, 9 ; (in D. Acadianum these teeth are, on the outside' 

 simple almost to the base, and plicated on the inner side, while 

 in this species they are plicated all around like the inner maxillary 

 teeth) : (4) The form of the skull, which has the orbits larger in 

 proportion, and is also shorter and broader. On the other hand, 

 when we have described the species of Hylonomus, it will be seen 

 that this animal, except in size, differs from them quite as widely 

 as does D. Acadianum. 



The distinctness of D. Oweni is further confirmed by the fact 

 that I possess small jaw bones of Dendrerpeton, about the size of 

 those of this species, but having the teeth similar in form to those 

 of the larger species ; these I suppose to have belonged to young 

 individuals. 



On examining the figures, it will be seen that the bones of the 

 skull were corrugated as in the large Dendrerpeton, but with a 

 smaller pattern. The forms of the jaw-bones also, and of the ver- 

 tebrae, ribs, scapular bone, bones of the limbs, and bony scales, 

 are very similar, and indicate that in general form this creature 

 was not far removed from its larger relative. The bones of the 

 foot, represented in Fig. 14, especially deserve attention. This is 

 the most perfect foot of Dendrerpeton hitherto found ; and I have 

 enlarged it in the figure, in order more distinctly to show its parts. 

 It presents three long toes, with traces of a smaller one at each 

 side, so that there were probably five in all. If these toes be 

 compared with the footprints on the slab discovered by Dr. Hard- 

 ing, represented in PI. I, Fig. 2, it will be seen that they very 

 closely correspond, though the toes of the present species are 

 much smaller. The footprints are precisely those which we may 

 suppose an animal of the size of Dendrerpeton Acadianum would 

 have made, if, as the bones found render in every way probable, 

 this larger species had a foot similar to that of D. Oweni. I sup- 

 pose, for this reason, that these footprints are really those of Den- 

 drerpeton Acadianum] and that this species continued to exist 

 from the time of the lower coal measures, to the period when 

 those higher beds of the series, in which its bones are found at 

 the Joggins, were deposited. 



The present species must have lived in the same places with 

 its larger relative ; but may have differed somewhat in its habits. 



