300 THE OLDEST AIR-BREATHERS 



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

 that the conditions in which these forests may have flourished 

 for centuries 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 noticeable 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 

 SigillaricBy and still more eminently the Calami/es, were suit- 

 able to such stations. There is direct evidence that the nuts 

 named 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 Equiseta, have produced spores with elaters cap- 

 able 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 dissemination. I have elsewhere proved ^ 

 that at least some species of Calaniiies were, by their mode of 

 growth, admirably fitted for growing amid accumulating sedi- 

 ment, and for promoting its accumulation. 



The reptiles of the coal formation are probably the oldest 

 known to us, and possibly, though this we cannot affirm, the 

 highest products of creation in this period. Supposing, for 

 the moment, that they are the highest animals of their time, 

 and, what is perhaps less hkely, 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 well as on the land. The plant feeders of the 

 period, on the land at least, are all invertebrates, as snails, 

 * ** Acadian Geology," chapter on Coal Plants. 





