166 AIR-BREATHERS OF THE COAL PERIOD. 



nomus aciedentatus, described in Section VIII, and Hyfarpetom 

 Dawsoni, Section X, are each represented by only a single speci- 

 men, and these did not occur in proximity to any of the portions 

 of cuticle, except that the appendages in PI. IV, fig. 32, were 

 found near a specimen of the former. Of the three remaining 

 species, Dendrerpeton Oweni, from its size, the number of speci- 

 mens found, and the juxtaposition of their bones to the fragments 

 of cuticle, appears to have the best claim to the integument in- 

 cluded under Nos. 1,2, and 3 ; and in this case, while the crea- 

 ture had its throat, and perhaps its abdomen, armed with bony 

 scales, its upper parts and tail, as well as its limbs, had a uniform 

 covering of small thin imbricated horny scales, in the manner of 

 many modern reptiles. 



If the remaining portions of integument, Nos. 4 and 5, as would 

 seem likely, belonged to two species, both of smaller dimensions, 

 there would seem little reason to doubt that these were Hylono- 

 mus Lyelli (Section VII) and H. Wymani (Section IX). In 

 this case, both of these species must have possessed a highly or- 

 nate covering of horny scales and appendages, comparable with 

 that of any of the modern lizards, while there seems good reason 

 to believe, as stated in a previous paper, that they were in part 

 protected by bony scales somewhat like those of Dendrerpeton/, 

 These points, however, we shall consider more in detail under 

 the sections which refer to the species of Hylonomus. 



Before leaving these curious specimens of ancient skin, the most 

 ancient I suppose known to exist, it is of interest to observe that 

 the thicker portions, when broken across, have the aspect of jet, 

 or of pure shining coal, and that thin slices, under the microscope, 

 have the same rich brown colour with that material, though rather 

 more translucent. When burned, fragments of the substance 

 give a strong flame, and a bituminous and ammoniacal odour. We 

 have thus an example of the production of coal from animal mem- 

 brane, no doubt gelatinous and homy in the first instance, but 

 which has proved itself capable of the same chemical changes 

 that have been experienced by the vegetable matter buried with 

 it. In order that this substance sho ild be preserved in this way,, 

 it would be necessary that it should either be kept dry and hard, 

 or that it should be immediately buried in matter impervious to 

 air, and kept moist. The latter conditions are the more probable* 

 The preservative qualities of the peaty vegetable matter imbedded 

 with it must also be considered ; and it is possible that these hoi- 



