224 ON APHYLLOSTACHYS. 
columnar'}* (including in this last species Calamites arenaceus), both 
otherwise leading plants of the Trias, are regarded as doubtful excep- 
tions to this generalization. 
In the Paleozoic period only 5 [6] of the 55 species of the Upper 
Devonian flora descend to the Lower Coal formation, viz. Sphenopteris 
' petiolufa, S. Devonica, S. refracta, S. disserta, S. imbricata, and Cala- 
mites transitions . Of the 185 species of the Lower Coal formation 
only 7 are found also in the Upper, viz. Sphenopteris obtusiloba, lly- 
menophjllites quercifolins, Cyatheites asper, Schizopteris lactuea, Sa- 
genaria aculeate, S. rugosa, and Neuropteris Loshii. The last is, of all 
fossil plants, as already mentioned, that which has enjoyed the longest 
life, extending from the Lower Coal formation to the Permian. The 
Upper Coal flora, which has about 814 species, has 19 in common with 
the Permian (which contains 272), viz. Gyromyces Jnmomt, Annulana 
floribtinda, Asterophyllites rigidns, Sphenopteris tridaciylites, S. arte- 
Ptisiafolia, Neuropteris tenui folia, N. ligulata, Alethopteris similis, 
Cyatheiles Schlotheimii, C. arbor escens, C. Oreopteridis, G. dentatus, 
Hemitelites cibotioides, Pacopte.ris plumosa, Sigillaria (and Stig^rta), 
Cordaites principalis, Cyclocarpus tuberosus, Noggerathia palmaformis 
and IFitlcliia piniformis. 
In the Flora of the Trias we find a less marked boundary towards 
that of the Jura than amongst its different divisions. Eqaiseldes 
volumnaria (Calamites arenariim) is met with both in the Jiu 
Sandstein and the Kcuper. On the other hand, the Keuper has, m 
common with the lower division of the Jura period (Lias), three spe- 
cies {Equisetites Minister i, Tm/iopteris marantacea, and Camptopten* 
M ilmteria « w) • the Lower Jura, or Lias, with the Middle Jura Ale- 
thopteris JFhitbiensis, A. Nebbensii, Tan'opUrit villata, F terophyU'"' 1 
minus, and Nilsonia compta ; and the Middle Jura with the VVea 
clay, Cyclopteris Ilutloni. . 
The Flora of the Jura period is clearly separated from that of « 
Cretaceous formation, and this again from the Tertiary, •**"* 
the Cretaceous beds we have for the first time genuine leaf-p an s 
i. e. Dicotyledons which are not Gymnosperms. 
> 
• 
In the Flora of the Tertiary period we have an increasing appW^. 
mation to, and greater affinity with that of the present, and a so r^ 
quent transition of speci from one division into anothei, a 
through all divisions to the present, as was first shown by me m 
