CONCLTTSIOX. 307 



regarded as giving more than an approximate estimate of the 

 composition of each flora. It is prohahle that the vegetation 

 which has left fairly abundant traces in the Wealden sediments 

 of the South-East of England and in the Inferior Oolite beds of 

 Yorkshire, flourished under very similar climatal and physical 

 conditions. 



A comparison of the Inferior Oolite plants with those of Rhaetic 

 age from Germany, Scania, and other regions leads us to recognize 

 a few examples of what appear to be identical species, e.g., Podo- 

 zamites lanceolatus and Sphenopteris princeps. Several instances of 

 closely related types have also been pointed out in the introductory 

 and systematic sections of this volume. 



"We may next briefly consider some of the more conspicuous 

 members of the Inferior Oolite flora from the point of view of 

 their resemblance to otber fossil types as well as to recent plants. 



Equisetales. Equisetites columnar is is one of the commonest and 

 most characteristic plants in the Yorkshire flora. Its abundance 

 lends support to the view that the small seams of coal met with 

 in the strata of the Estuarine Series were probably in great measure, 

 if not entirely, formed from the remains of the Equisetaceous 

 plants which grew in the Jurassic swamps. The thicker stems 

 described under the name Equisetites Beani are comparable in size 

 to E. arenaceus of Triassic age, and surpass in diameter the 

 characteristic Rhaetic form E. Jfuensteri. Compared with such 

 "Wealden species as Equisetites Lyelli and E. Burchardti the Inferior 

 Oolite Equisctaceae are distinguished by the greater thickness of 

 their stems, and in this respect they carry us a stage further from 

 the modern Horsetails towards the arborescent representatives of 

 the Equisetales, which flourished during the Triassic and Palaeozoic 

 epochs. 



Filices. Among the Inferior Oolite ferns there are several 

 species which cannot be referred to any particular subdivision of 

 the filices, but on the other hand we have sufficient evidence in 

 many cases to admit of a satisfactory identification of family 

 affinities. The species Sagenopteris Phillipsi, which for reasons 

 already stated I have included among the filices rather than the 

 Rhizocarpeae, may not improbably belong to the Polypodiaceae, 

 but of this we have not sufficient evidence. The species is of 

 interest as a common type, which forms a connecting link on 

 the one hand with the older and larger Rhaetic forms Sagenopteris 



