86 AIR-BREATHERS OF THE COAL PERIOD. 



swimming or walking on soft mud, or both. That the hind limb 

 was adapted for walking is shown, not merely by the form of the 

 bones, but also by that of the pelvis, the best preserved specimen 

 of which is represented in Fig. 28 ; but an iliac limb of still larger 

 size is figured in the Journal of the Geological Society, Vol. IX. 



The external scales are thin, oblique-rhomboidal or elongated- 

 oval, marked with slight concentric lines, but otherwise smooth, 

 and having a thickened ridge or margin ; in which they resemble 

 those of Archegosaurus, and also those of Pholidogaster pisciformis, 

 recently described by Huxley from the Edinburgh coal-field, — an 

 animal which indeed appears in most respects to have a close affi- 

 nity with Dendrerpeton. The microscopic structure of the scales 

 is quite similar to that of the other bones, and different from that 

 of the scales of ganoid fishes, the shape of the cells being batra- 

 chian as in Fig. 11. Figs. 18 and 19 exhibit different forms of 

 the scales. 



"With respect to the affinities of the creature, I think it is ob- 

 vious that it presents ,some points of resemblance, on the one 

 hand to Archegosaurus, and on the other, to Labyrinthodon ; and 

 that it has the same singular mixture of ichthyic, batrachian, and 

 reptilian characters which distinguish these ancient animals, and 

 which give them the appearance of prototypes of the reptilian 

 class. Professor Owen regards Archegosaurus as the type of the 

 order Ganocephala, which he characterizes as having the head 

 protected by sculptured and polished ganoid plates, no occipital con- 

 dyles, teeth with converging folds of cement at their basal half, the 

 notochord persistent, the ribs short and straight, the limbs natato- 

 ry and small ; and holds that Dendrerpeton approaches more nearly 

 to this order than to the Labyrinthodonts. But at the time when 

 this opinion was expressed, he was not fully aware of the develop- 

 ment of the limbs and ribs, and of the ossified condition of the 

 vertebrae ; characters which, with the form of the skull, the ar- 

 rangement of the teeth, and the probable possession of occipital 

 condyles, appear to determine the scale in favour of the Labyrin- 

 thodonts. At the same time it must be admitted that Dendrerpe- 

 ton is far removed from the typical genus Labyrinthodon, and 

 that in the characters in which it differs, it leans toward Arche- 

 gosaurus; closely resembling in thisits contemporary Pholidogaster 

 pisciformis already referred to. 



This ancient inhabitant of the coal swamps of Nova Scotia, 

 was, in short, as we often find to be the case with the earliest 



