312 CONCLUSION. 



certainly an Araucarian type ; Pagiophyllum Williamsoni recalls 

 Araucaria excelsa, and Cryptomerites divaricatus bears a close 

 resemblance to Araucaria Cunninghamii. The vegetative characters 

 of Brachyphyllum mamillare invite a comparison with the Tasmanian 

 genus Arthrotaxis. 



Admitting the clanger of drawing conclusions from such imperfect 

 data as the Conifers afford, we are probably justified in asserting 

 that Araucaria, Arthrotaxis, and possibly Podocarpus and Agathis, 

 among existing genera agree the most nearly with Inferior Oolite 

 types. The Abietineae have no certain representives in the East 

 Yorkshire flora ; this family assumed a much more important 

 position in the succeeding Wealden and Lower Cretaceous 

 vegetation. 



In conclusion, we may endeavour to answer the question, what 

 assemblage of recent plants would we select as best illustrating 

 the character of the Inferior Oolite vegetation? The large 

 Equisetums of the marshes of South America most nearly recall 

 the fossil forms, while a species of Selaginella, a genus of wide 

 distribution, and represented by several tropical examples in the 

 Southern Hemisphere, may be taken as affording the nearest approach 

 to Lycopodites falcatus. Among Ferns we have Matonia pectinata, 

 Pipteris conjugata, Todea barhara, species of Lygodium and Anemia, 

 Balantium (Picksonia), and Thyrsopteris. Among recent Cycads, 

 the fronds of certain species of Zamia, Encephalartos, Bowenia, and 

 others recall the habit of some of the Jurassic types. Ginkgo biloba 

 alone survives as a representative of the Ginkgoales, and is probably 

 but slightly different from its Jurassic ancestors. Of existing 

 Conifers we may select Araucaria, Arthrotaxis, and Podocarpus as 

 types exhibiting the nearest approach to the Inferior Oolite species. 

 It is in the Southern tropics that we must look for existing forms 

 which afford the most striking links between the vegetation of 

 to-day and that which has left imperfect records in the Jurassic 

 sediments of the Yorkshire coast. The climate was presumably 

 more tropical than that of North Europe at the present day ; 

 there is no evidence that the plants of Jurassic times grew under 

 conditions which induced xerophytic characters, moisture being 

 probably abundant and favourable to the luxuriant growth of 

 Equisetums and Eerns. 



