288 AIR-BREATHERS OF THE COAL PERIOD. 



Farther, it is be observed that the conditions of submergence and 

 silting up which were favorable to the preservation of specimens of 

 Sigillarice as fossils, must have been precisely those which. 

 were destructive to them as living plants ; and on the contrary that 

 the conditions in which these forests may have flourished for cen- 

 turies, must have been those in which there was little chance of 

 their remains being preserved to us, in any other condition at 

 least than that of coal, which reveals only to careful microscopic 

 examination the circumstances, whether aerial or aquatic, under 

 which it was formed. 



It is also to be observed that, in conditions such as those of the 

 coal-formation, it would be likely that some plants would be 

 specially adapted to occupy newly emerged flats and places liable 

 to inundation and silting up. I believe that many of the 

 Sigillarice, and still more eminently the Calamites, were suitable to 

 such stations. There is direct evidence that the nuts of Sigillarice 

 (Trigonocarpa) were drifted extensively by water over submerged 

 flats of mud. Many Cardiocarpa were winged seeds which may 

 have drifted in the air. The Calamites may, like modern Equise- 

 ta, have produced spores with elaters capable of floating them in 

 the wind. One of the thinner coals at the Joggins is filled with 

 spores or spore-cases that seem to have carried hairs on their 

 surfaces, and may have been suited to such a mode of dissemina- 

 tion. I have elsewhere proved that at least some species of Cala- 

 mites, were by their mode of growth admirably fitted for growing 

 amid accumulating sediment and for promoting its accumulation. 



These and other facts to be ascertained only by a careful and 

 minute study of the coal formation and its fossils, are essential to 

 a right understanding of the complicated conditions involved in 

 the growth of these great deposits ; and notwithstanding the im- 

 mense mass of facts which has been collected, there is still no de- 

 partment of geology more encumbered with crude hypotheses and 

 hasty generalizations, than that which relates to the history of the 

 carboniferous period. 



The reptiles of the coal formation are probably the oldest known 

 to us, and possibly, though this we cannot affirm, the highest pro- 

 ducts of creation in this period. Supposing, for the moment, 

 that they are the highest animals of their time, and what is 

 still less likely, that those which we know are a fair average of the 

 rest, we have the curious fact that they are all carnivorous, and 

 the greater part of them fitted to find food in the water as welljas 



