Simmons, Remarks about tbe Relations of the Floras etc. 
183 
the tertiary origin of every species and genus of the present 
floras of the regions in question, as in many cases our present 
knowledge of their distribution will probably prove incomplete, 
but in many other instances I think it must be possible to 
settle already now the question about the tertiary area. 
At first I will take into consideration such genera as must 
have had their sole home or at least have been principally re- 
presented in the tertiary Polar Sea, as can be concluded from 
Table VIII. 
Such are: 
Streblonema 
Maria 
Phycoceiis 
Agarum 
CJiaetopteris 
Laminaria 
Desmotrichum 
Lithoderma 
Punctaria 
Fucus 
Coilodesme 
Pliyllophora 
Phleospora 
Cystoclonium 
Striaria 
AgardJiiella 
Dictyosiplion 
Turnerelia 
Eudesme 
Futhora 
Castagnea 
Halosaccion 
Leathesia (?) 
Rhodomela 
Balfsia (?) 
Odonthalia 
Chorda 
Ptilota 
Phyllaria 
Dilsea. 
Genera that can in consequence of their present distribu¬ 
tion hardly have been anything but tertiary-atlantic are: 
Sorocarpus 
Dichosporangimn 
Isthmoplea 
Halopteris 
Physematoplea 
Delamarea 
Pogotriclmm 
Artlirocladia 
Gobici 
Leptonema 
Halothrix 
Cutleria 
ScapJiospora 
PLimanthalia 
Pelvetia 
Ascophyllum 
Halidrys 
Naccaria 
Sphaerococcus 
Grinnellia 
Hcdurus 
Compsoth amnion 
Dudresnaya 
J^nrrpllnria 
Tdopteris Polyides. 
Of course the above lists cannot have anv claim to be 
t 
reckoned as complete, probably still rnore genera could be 
added to the former, and as to the latter there is always some 
doubt left if not their tertiary home can still have been on the 
north side of the landbridge (cf. the above quotation from 
Reinke), but then we must either suppose that tliey have been 
destroyed by the progress of glaciation on their way to Bering 
Straft or also alter the previous supposition that the flora in the 
old Polar Sea has been a uniform one, a theory that is rather 
