AIR-BREATHERS OF THE COAL PERIOD. 85 



toe lower jaw there was a uniform series of conical teeth, not per- 

 ceptibly enlarged toward the front; at least thi3 is the case in the 

 only specimen at present in my collection (Fig. 16) ; which is 

 however merely an imperfect cast in hard sandstone. 



The scapular and sternal bones seem to have been well devel- 

 oped and strong, but only portions of them are known (Fig. 25.) 

 The fore limb of the adult animal, including the toes, must have 

 been four or five inches in length, and is of massive proportions. 

 The bones were hollow, and in the case of the phalanges the bony 

 walls were thin, so that they are often found crushed fiat. The 

 humerus however was a strong bone, with thick walls and a can- 

 cellated structure toward its extremities ; still even these have 

 sometimes yielded to the great pressure to which they have been 

 subjected. Fig. 26 shows the humerus of the original specimen 

 of the species, and Fig. 10 exhibits a series of sections of a similar 

 bone, probably the humerus of a smaller individual. The cavity 

 of the interior of the limb-bones is usually filled with calc-spar 

 stained with organic matter, but showing no structure ; and the 

 inner side of the bony wall is smooth, without any indication of 

 cartilaginous matter lining it. 



The vertebrae, in the external aspect of their bodies, remind one 

 of those of fishes, expanding toward the extremities, and being 

 deeply hollowed by conical cavities, which appear even to meet in 

 the centre. There is however a large and flattened neural spine. 

 The vertebrse are usually much crushed, and it is almost impos- 

 sible to disengage them from the stone. Fig. 21 exhibits the usual 

 form, and Fig. 22 another ; which, in its long neural and haemal 

 spines, reminds us of the caudal vertebrae of those batrachians and 

 reptiles which have tails flattened for swimming, and probably in- 

 dicates that this was the case with Dendrerpeton. Fig. 23 is a 

 transverse section of a somewhat crushed vertebra, showing its os- 

 sified centrum and neural spine, and also the microscopic struc- 

 ture of the bone. The ribs are long and curved, with an expanded 

 head, near to which they are solid, but become hollow towards the 

 middle ; and the distal extremities are flattened and thin walled. 

 The posterior limb seems to have been not larger than the ante- 

 rior, perhaps smaller. The bones represented in Fig. 27, which I 

 refer to this member, probably belonged to a somewhat smaller 

 individual than that to which the humerus in Fig. 26 belonged. 

 The tibia is much flattened at the extremity, as in some labyrin- 

 thodonts,and the foot must have been broad, and probably suited for 



