THE OLDEST AIR-BREATHERS 259 



of Trilobites, the weathered Laurentian rocks, the wind ripples 

 in the Potsdam sandstone, the rich fossils of the limestones, 

 testify to these things. The existence of such conditions 

 would lead us to hope that land animals may yet be found in 

 these older formations. On the other hand, the gradual failure 

 of one form of life after another, as we descend in the geo- 

 logical series, and the rarity of fishes and land plants in the 

 Silurian rocks and their absence from the Cambrian, might 

 induce us to believe that we have here reached the beginning 

 of animal life, and have left far behind us those forms that 

 inhabit the land. 



Even in the Carboniferous period, though land plants 

 abound, air-breathers are not numerous, and most of them 

 have only been recently recognised. We know, however, 

 with certainty that the dark and luxuriant forests of the coal 

 period were not destitute of animal life. Reptiles 1 crept 

 under their shade, land snails and millipedes fed on the 

 rank leaves and decaying vegetable matter, and insects flitted 

 through the air of the sunnier spots. Great interest attaches 

 to these creatures; perhaps the first-born species in some of 

 their respective types, and certainly belonging to one of the 

 oldest land faunas, and presenting prototypes of future forms 

 equally interesting to the geologist and the zoologist. 



It has happened to the writer of these pages to have had 

 some share in the finding of several of these ancient animals. 

 The coal formation of Nova Scotia, so full in its development, 

 so rich in fossil remains, and so well exposed in coast cliffs, 

 has afforded admirable opportunities for such discoveries, 

 which have been so far improved that at least twenty-five out 

 of the not very large number of known Carboniferous land 

 animals have been obtained from it. 2 The descriptions of 



1 I shall use the term reptile here in its broad, popular sense, as including 

 Batrachians as well as reptiles proper. 



2 It appears that about a hundred species of Carboniferous reptiles 



