[Vol. 2 



90 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



southern mollusc genus Tapes, which shows that the average 

 annual temperature must have been between 8 and 9°C. 



(Brogger, '00). 



Various opinions have been expressed as to whether the 

 warmest period was before, at, or a little after, the maximum 

 of the Littorina Subsidence in Sweden. This is of little im- 

 portance here, but what is more important is that the earliest 

 remains of stone implements in Norway date from this 

 warmest period (the Tapes Period), which, therefore, in the 

 opinion of archaeologists, must be assumed to have been about 

 7,000 years ago. This accords well with G. de Geer's calcu- 

 lations from the number of clay strata. 



J. Holmboe has found the following species of plants, to- 

 gether with Quercus pedunculated, in Norwegian peat-bogs: 

 Acer platanoides, Aspidium Thelypteris, Bidens cernua, B. 

 tripartita, Calla palustris, Car ex stellulata, C. vesicaria, Cer- 

 atophyllum demersum, Crambe maritima, Fraxinus excelsior, 

 Galeopsis Tetrahit, Iris Pseudacorus, Myrica Gale, Naias 

 flexilis, Naumburgia thyrsiflora, Oxalis Acetosella, Peuce- 

 danum palustre, Potamogeton praelongus, Ranunculus repens, 

 Rub us fruticosus, Ruppia rostellata, R. spiralis, Scirpus ma- 

 ritimus, Sorbus Aucuparia, Sparganium ramosum, Stachys 



sylvatica, Thalictrum flavum, Tilia cordata, Viola sp., Zostera 

 marina. 



It will at once be seen that a good many of these species 

 were enumerated as having been found in the south of Sweden 

 during an earlier period, i.e., with Pinus sylvestris. This 

 agrees very well with the assumed immigration route through 

 Sweden, as it must have taken a considerable length of time 

 for these plants to spread through Sweden into southern 

 Norway. It must not, however, be forgotten that the occur- 

 rences of plants in the peat-bogs indicate only the minimum 

 length of time of their existence in the place in question, as 

 they may very well have lived there for a long time before 

 being deposited in a peat-bog, to be found there th rough the 



!-> 



of a botanist 



above. Gunnar Andersson has found 



following fossil snecies in the Oak Period in Sw 



