THE OLDEST AIR-BREATHERS 



relation to the vegetable fossils still remains to be worked up. 

 It is with the more striking fact of the discovery of the remains 

 of a reptile in the coal measures that we have now to do. 



The South Joggins Section is, among other things, remark- 

 able for the number of beds which contain remains of erect 

 trees imbedded in situ : these trees are for the most part 

 Sigillariae, those great-ribbed pillar-like trees which seem to 

 have been so characteristic of the forests of the coal formation 

 flats and swamps, and so important contributors to the forma- 

 tion of coal. They vary in diameter from six inches to five feet. 

 They have grown on underclays and wet soils, similar to those 

 on which the coal was accumulated ; and these having been 

 submerged or buried by mud carried down by inundations, 

 the trees, killed by the accumulations around their stems, 

 have decayed, and their tops being broken off at the level of 

 the mud or sand, the cylindrical cavities left open by the dis- 

 appearance of the wood, and preserved in their form by the 

 greater durability of the bark, have been filled with sand and 

 clay. This, now hardened into stone, constitutes pillar-like 

 casts of the trees, which may often be seen exposed in the 

 cliffs, and which, as these waste away, fall upon the beach. 

 The sandstones enveloping these pillared trunks of the ancient 

 Sigillariae of the coal, are laminated or bedded, and the 

 laminae, when exposed, split apart with the weather, so that the 

 trees themselves become broken across ; this being often 

 aided by the arrangement of the matter within the trunks, in 

 layers more or less corresponding to those without. Thus one 

 of these fossil trees usually falls to the beach in a series of 

 discs, somewhat resembling the grindstones which are exten- 

 sively manufactured on the coast. The surfaces of these 

 fragments often exhibit remains of plants which have been 

 washed into the hollow trunks, and have been imbedded 

 there ; and in our explorations of the shore, we always care- 

 fully scrutinized such specimens, both with the view of observ- 



