300 T. Davidson — Notes on Continental Geology. 



of the stem is precisely the same as in Lepidodendron, to which it is 

 closely allied. Externally it has a very different appearance, being 

 either a simple cylindrical column, or in some species dividing dicho- 

 tomously into a few thick branches. The leaves are long, slender, 

 and parallel-sided. Their scars ornament the older portions of the 

 stem, on which they are arranged in perpendicular series with in- 

 tervening furrows. 



The fruit has been described by Goldenberg. It agrees with that 

 which I have described in Flemingites except that the small sporangia 

 are scattered in an irregular patch over the dilated base of an ordi- 

 nary leaf, and this confirms the systematic position which I have 

 given to Sigillaria.^ 



The ferns and other genera which I have described may be con- 

 sidered the types of the plants to which we are indebted for our 

 stores of mineral fuel. They grew in extensive level plains, their 

 fleshy roots penetrating the soft mud which formed the surface 

 soil, or the spongy layer of vegetable matter which covered it. 

 The moist atmosphere (not at all likely to have been charged with 

 more carbonic acid gas than that of our own day) would encourage 

 the growth of cellular parasites and epiphytes, and the Aroid dis- 

 covered by Dr. Paterson, with the several species of Antholithes, 

 most probably represent races of epiphytes of a much higher or- 

 ganization than the cryptogamic trees on which they flourished. 



Coniferous trees may have grown on the margins of the plain, 

 but their proper habitat seems to have been the higher ground, from 

 which an occasional stem was floated down by running water to the 

 plains below. What plants were associated with the Conifers in 

 those upland regions, is as yet quite unknown. The Flora of the 

 coal period as at present ascertained is that of the plains. And this 

 is of high interest, apart from the economic value of its products, 

 because it reveals to the biologist an assemblage of plants agreeing 

 in all essentials with some of the humble members of our present 

 Flora, but attaining at so early a period in the history of the world 

 a development not only in size but in organization, greatly in advance 

 of their modern allies. 



n. — Notes on Continental Geology and Paleontology. 



By Thomas Davidson, F.E.S., F.G.S, 



{Continued from p. 263). 



(Paet IV.) 



IN the June Number (p. 251), we gave Messrs. Pictet and Lory's 

 most recent views on the disputed age of those beds which con- 

 tain the Tereiratula diphya or T. viator of Pictet. In order to com- 



1 For a lengthened examination of the affinities and structure of this genus, see 

 a Memoir read to the Geological Society, at its meeting ou March 24th, and to he 

 puhlished in its Quarterly Journal on the 1st of August next. 



