Although the present work is essentially devoted to the prac- 

 tical part of gardening, it may not be out of place to remind 

 readers that, from the numerous interesting scientific discoveries 

 for which the present century is justly famous, it is certain that 

 Ferns and Lycopods formed the earliest vegetation of our Globe. 

 It has been proved beyond doubt that the formation of coal, 

 during the carboniferous period, was unquestionably due to the 

 existence of Ferns and Lycopods, which, in those days, attamed 

 really gigantic dimensions, since well-preserved fossil specimens 

 of these plants, measuring QSft. in height and 30ft. in cir- 

 cumference, have been found in various collieries here and on 

 the Continent. The Equisetums, or " Horsetails," of the present 

 day found in this country are but diminutive representatives of 

 another genus of flowerless gigantic trees which greatly helped the 

 ormation of the combustible materials, bituminous coal and 

 anthracite. Correvon, in his interesting dissertation, " Les 

 Fougeres dans les Ages Geologiques," tells us that in coal-mines 

 and in slate-quarries over 900 fossil species of Ferns, divided 

 into more than 160 genera, have already been collected and 

 determined. The species in existence then have all disappeared, 

 and have been replaced by plants more modest in appearance 

 and of smaller dimensions which, although deprived of the gor- 

 geous colours particular to flowering plants, have, so far as grace, 



