INTRODUCTION 5 



Prof. Seward of Cambridge. Ferns, Cycadophyta, and 

 Conifers are the most characteristic forms of this 

 period. The Oolitic strata, specially the Purbeck beds 

 at the top of the system, also abound in Cycad-like 

 remains, though most of the Mesozoic plants with the 

 habit of Cycads were very different from any members 

 of the family as now existing. The Wealden and 

 Upper Jurassic of the United States are extraordinarily 

 rich in Cycadophyta, recently investigated, with brilliant 

 results, by Dr. Wieland of Yale. Such remains as we 

 have from the Trias, e.g. the New Red Sandstone, have 

 a still more old-world character (including strange and 

 gigantic Horsetails and Lycopods), and prepare us for 

 the Palaeozoic system. 



When we descend to the Permian we find ourselves 

 at once among the characteristic Palaeozoic families — 

 especially the Sigillarias and Calamites, together with 

 extinct Spermophytic types. This brings us to the 

 Carboniferous formation, the flora of which is the richest 

 and most remarkable which the rocks have preserved 

 for us. The Carboniferous formation includes many 

 other strata besides those of the Coal-measures, which 

 belong to its upper part. The Coal-measures them- 

 selves reach a thickness of 12,000 feet, and represent 

 a prodigious period of time. Fortunately, however, 

 we are not limited for our specimens to this part of 

 the formation, extensive as it is, for there are productive 

 beds down to the base of the Lower Carboniferous 

 rocks ; when we find well-preserved plants much older 

 than the Coal-measures, we may think ourselves 

 specially fortunate. The plant -remains of the next 

 great formation, the Devonian, though scanty compared 



