328 PROCEEBINGS OF TKE GEOLOGICAL SOCIETY. [May 7, 



better represented in the Devonian than in the Carboniferons deposits, 

 and several Carboniferous genera are wanting in the Devonian. 



2. Some species which appear early in the Devonian Period con- 

 tinue to its close without entering the Carboniferous ; and the great 

 majority of the species, even of the Upper Devonian, do not reap- 

 pear in the Carboniferous Period ; but a few species extend from the 

 Upper Devonian into the Lower Carboniferous, and thus establish a 

 real passage from the earlier to the later flora. The connexion thus 

 established between the Upper Devonian and the Lower Carboni- 

 ferous is much less intimate than that which subsists between the 

 latter and the true Coal-measures. Another way of stating this is, 

 that there is a constant gain in number of genera and species from 

 the Lower to the Upper Devonian, but that at the close of the 

 Devonian many species and some genera disappear. In the Lower 

 Carboniferous the flora is again poor, though retaining some of the 

 Devonian species ; and it goes on increasing up to the period of the 

 Middle Coal-measures, and this by the addition of species quite di- 

 stinct from those of the Devonian Period. 



3. A large part of the difference between the Devonian and Car- 

 boniferous Ploras is probably related to different geographical condi- 

 tions. The wide swampy flats of the Coal Period do not seem to 

 have existed in the Devonian era. The land was probably less ex- 

 tensive and more of an upland character. On the other hand, more- 

 over, it is to be observed that, when in the Middle Devonian we find 

 beds similar to the underclays of the Coal-measures, they are filled, 

 not with Stigmaria, but with rhizomes of PsilopJiyton ; and it is only 

 in the Upper Devonian that we find such stations occupied, as in the 

 Coal-measures, by Sigillaria and Calamites. 



4. Though the area to which this paper relates is probably equal 

 to any other in the world in the richness of its Devonian Plora, still 

 it is apparent that the conditions were less favourable to the pre- 

 servation of plants than those of the Coal Period. The facts that 

 so large a proportion of the plants occur in marine beds, and that 

 so many stipes of Ferns occur in deposits that have afforded no 

 perfect fronds, show that our knowledge of the Devonian Flora is 

 relatively far less complete than our knowledge of that of the Coal- 

 formation. 



5. The Devonian Flora was not of lower grade than that of the 

 Coal Period. On the contrary, in the httle that we know of it we 

 find more points of resemblance to the Floras of the Mesozoic Period, 

 and of modern tropical and austral islands, than in that of the true 

 Coal-formation. "We may infer from this, in connexion with the 

 preceding general statement, that in the progress of discovery very 

 large and interesting additions will be made to our knowledge of 

 this flora, and that we may possibly also learn something of a land 

 fauna contemporaneous with it. 



6. The fades of the Devonian Flora in America is very similar to 

 that of the same period in Europe, yet the number of identical 

 species does not seem to be so great as in the coal-fields of the two 

 continents. This may be connected with the different geographical 



