ff8 



THE GEOLOGICAL HISTORY OF PLANTS. 



we may add the appearance of these macrospores in coals 

 and shales of the Carboniferous period, tliough there in 

 association with other forms. 



It is also to be observed that the Erian shales, and the 

 Forest of Dean beds described by Wethered, are marine, 

 as shown by their contained fossils ; and, though I have 

 no certain information as to the Tasmanite and Austra- 

 lian white coal, they would seem, from the description of 

 Milligan, to occur in distinctly aqueous, possibly estua- 

 rine, deposits. Wethered has shown that the discs de- 

 scribed by Huxley and Newton in the Better-bed coal 

 occur in the earthy or fragmentary layers, as distin- 

 guished from the pure coal. Those occurring in cannel 

 coal are in the same case, so that the general mode of 

 occurrence implies water-driftage, since, in the case of 

 bodies so large and dense, wind-driftage to great distances 

 would be impossible. 



These facts, taken in connection with the differences 

 between these macrospores and those of any known land- 

 plant of the Palaeozoic, would lead to the inference that 

 they belonged to aquatic plants, and these vastly abundant 

 in the waters of the Erian and Carboniferous periods. 



It is still further to be observed that they are not, in 

 the Erian beds, accompanied with any remains of woody 

 or scalariform tissues, such as might be expected in con- 

 nection with the debris of terrestrial acrogens, and that, 

 on the other hand, we find them enclosed in cellular 

 sporocarps, though in the majority of cases these liave 

 been removed by dehiscence or decay. 



These considerations, I think, all point to the prob- 

 ability which I have suggested in my ])apers on this sub- 

 ject referred to above, that we have in these objects the 

 organs of fructification of plants belonging to the order 

 Bhizocarpece, or akin to it. The comparisons which I 

 have instituted with the sporocarps and macrospores of 

 these plants confirm this suggestion. Of the modern 



