252 THE JOURNAL OF BOTANY 



and for another equally important reason. There is a rare beech- 

 wood land-shell, Rolph's Clausilia, which is practically confined to 

 the south and south-west chalk beech-woods. It is found to be 

 widely distributed in Lincolnshire on chalk and limestone. It is 

 apparently now confined to ash-oak woods with us. There is a 

 connection also towards the southern fagesques through Notting- 

 hamshire and Northamptonshire, where the shell is sparingly 

 found in similar woods. How could this rare species have 

 become distributed so widely on our limestones without the aid of 

 its native fagesques ? The two districts named above as our only 

 beech-woods are the only spots where Buliminus montanus, 

 another distinct fagesque shell once reported for this county, is 

 likely to occur with us. So far as I know, neither of these old 

 beech-wood districts has been thoroughly searched for its asso- 

 ciated shells, so it is possible that the most striking evidence may 

 be turned up at any time. 



The wide range of Pinus before historic times and the general 

 indications which point to a similar history for Fagus just within 

 but rather beyond these times are not isolated facts. They fit in 

 with what we know about all the other species for which we 

 possess peat records, as w^ell as with the cultivation of the vine 

 as a field crop. All the facts which have come to light point 

 clearly one way. They demonstrate a former period of greater 

 heat, from more prolonged sunlight and milder winters well 

 within the Historic Period — detrimental to Pinus, but suitable 

 for Fagus-growth. Surely the high-level forests of the Pennines, 

 of pine, hazel, and bog-birch, point to the same conclusion ? They 

 are far above the present tree level of our existing normal tempe- 

 rature. I believe that all the facts that may be collected will 

 only tend to the same conclusion, as soon as we begin to enquire ; 

 and that is not all, for the same thing is going on to-day. 



There can be little doubt that in Lincolnshire the ash has 

 taken the place of the oak and beech, as certainly as Betula alba 

 and B. pubescens have ousted the pine in drier and moister 

 localities, all well within the Historic Period. It is certain, too, 

 that this process of change has not ceased with us. The yew 

 has gone from Lincolnshire as an areal species, though it was 

 quite common once, as in the parish of Cadney. A hundred and 

 twenty years ago Pimis was confined to a few isolated spots. 

 To-day I watch the same process in operation. The ash is being 

 slowly supplanted by the wych elm, and even that, as well as 

 every other species, fails in the struggle for existence in the open 

 with the sycamore, on account of its winged and far-carrying 

 seeds — this notwithstanding that the wych elm is better fitted for 

 our climate in all other respects. 



Anyone wishing to interpret logically and formulate clearly 

 our existing tree formations cannot safely ignore the change of 

 climate which has plainly taken place within historic times, 

 without misinterpreting some of the most important facts which 

 may be observed in our present woodland growths. It is not wise 

 to forsake the ground of fact for surmises, even about our pine 



