THE ANCIEXT AKD MODERX FLORAS OF MONTPELLIER. 219 



bably brought to us from Germany, is establishing itself in some of 

 our corn fields. 



The oriental RJiododendron ponticum sows itself so freelv in the 

 parks and plantations of some of our southern and western counties, 

 that it may perhaps be classed as a naturalized species of modern 

 introduction. 



Dr. Planchon could find only six species which had maintained 

 themselves in the spot or limited grounds where they had been 

 planted, although they had not spread further. We have many such, 

 but we do not usually include them in our Eloras. A few hedge 

 shrubs, such as Sjjircea salicifolia, in North Wales, may not have 

 been of ancient introduction, but we cannot ascertain that here any 

 more than at Montpellier, a single species introduced within the last 

 three centuries, has gained a footing in our natural woods, heaths, 

 moors, or pastures ; the period is too short for any very perceptible 

 change in the vegetation of uncultivated districts. 



In the Memoir on the calcareous tufas of the neighbourhood of 

 Montpellier, of which we have given the title above, Dr. Planchon 

 takes up the history of the vegetation at a much earlier period as 

 supplied to us by evidences derived from the impressions of stems, 

 leaves, flower, and fruits found in these deposits. 



The early portion of this Memoir is devoted to the geological 

 description of the nature, extent, and position of the tufas, and to a 

 description of the different theories propounded on their formation 

 and period. This is followed by an enumeration of the species of 

 plants of which impressions have been traced, discussing in the case 

 of each the evidences upon which its determination has been founded; 

 and in conclusion, the general aspect of the vegetation they exem- 

 plify is compared with that of the present day. The essay includes 

 a list of terrestrial and freshwater shells which have left their remains 

 or moulds in the same deposits, and, in an Appendix, an account 

 is given of a WiyacopJiila, the larva of which has left in them 

 tubular incrustations which had been mistaken for impressions of 

 roots. 



The tufas of the neighbourhood of Montpellier are nearly all 

 grouped in the valley of the Lez ; the largest and richest in remains 

 are below the village of Castelnau, spread over a space of at least 100 

 hectares (about 250 acres) from about a mile to a mile and a half 

 from the town, and near G-asconnet, occupying about 23 hectares 

 (nearly 60 acres) a mile and a half higher up the river. Several 

 smaller deposits further on have much fewer remains. 



Q 2 



