AIR-BREATHERS OF THE COAL PERIOD. 87 



forms of life, the possessor of powers and structures not usually, 

 in the modern world, combined in a single species. It was cer- 

 tainly not a fish, yet its bony scales, and the form of its vertebrae, 

 and of its teeth, might, in the absence of other evidence, cause it to 

 be mistaken for one. We call it a batrachian, yet its dentition, the 

 sculpturing of the bones of its skull, which were certainly no more 

 external plates than the similar bones of a crocodile, its ribs, and 

 the structure of its limbs, remind us of the higher reptiles ; and 

 we do not know that it ever possessed gills, or passed through a 

 larval or fish-like condition. Still, in a great many important char- 

 acters, its structures are undoubtedly batrachian. It stands, in 

 short, in the same position with the Lepidodendra and Sigillarioe 

 under whose shade it crept, which though placed by palaso-bota- 

 nists in alliance with certain modern groups of plants, manifestly 

 differed from these in many of their characters, and occupied a dif- 

 ferent position in nature. In the coal period, the distinctions of 

 physical and vital conditions were not well defined — dry land 

 and water, terrestrial and aquatic plants and animals, and lower 

 and higher forms of animal and vegetable life, are consequently 

 not easily separated from each other. This is no doubt a state of 

 things characteristic of the earlier stages of the earth's history, 

 yet not necessarily so ; for there are some reasons, derived from fos- 

 sil plants, for believing that in the preceding Devonian period 

 there was less of this, and consequently that there may then have 

 been a higher and more varied animal life than in the coal period.* 

 Even in the modern world also, we still find local cases of this 

 «arly union of dissimilar conditions. It is in the swamps of 

 Africa, at one time dry, at another inundated, that such interme- 

 diate forms as Lepidosiren occur, to baffle the classificatory pow- 

 ers of naturalists ; and it is in the stagnant unaerated waters, half 

 swamp, half lake or river, and unfit for ordinary fishes, that the 

 semi-reptilian Amia and Lepidosteus still keep up the characters 

 of their palaeozoic predecessors. 



The dentition of Dendrerpeton shows it to have been carnivo- 

 rous in a high degree. It may have captured fishes and smaller 

 reptiles, either on land or in water, and very probably fed on 

 dead carcases as well. If, as seems likely, the footprints referred 

 to in a previous section belong to Dendrerpeton, it must have fre- 

 quented the shores, either in search of garbage, or on its way to 



* See the author's paper on Devonian plants, Journal of the Geological 

 Society, Vol. xviii, p. 328. 



