CONCLUSION. 309 



Osmundaeea. Todites Williamsoni must have been one of the 

 most conspicuous and abundant ferns which flourished during the 

 Jurassic period. It is possible that Sphenopteris princeps should 

 also be included in this family, but we lack such convincing 

 evidence of affinity as is afforded by the fertile specimens of 

 Todites Williamsoni. The Rhaetic species described by Schcnk as 

 Acrostichites Goeppertianus appears to be barely distinguishable 

 from the Inferior Oolite species of Todites: from the "Wealden 

 plant-beds no satisfactory representative of the Osinundaccae has so 

 far been recorded. 



The Cyatheacea arc represented by such species as Coniopteris 

 In/uniiophylloides, one of the most characteristic of the Yorkshire 

 Coast ferns, C. quinqueloba, and C. arguta. There is a striking 

 resemblance between some of these fossil Cyatheaceae and the isolated 

 recent fern Tinjrxoptcris clegans. The Inferior Oolite flora was 

 characterized by an abundance of ferns of the Thyrsopteris type. 



Among Wealden ferns we have the genus Protoptcris, which 

 may probably be included as a member of the Cyatheaceae, a t)*pe 

 which extends into still more recent geological periods. 



Schizaacea:. In addition to the somewhat doubtful Ruffordia 

 <!< pperti of Wealden and Inferior Oolite age, we have an excellent 

 example of this family in the widely distributed Klukia exilis, 

 a species which may also be closely matched among Wealden ferns. 

 Neither the Cyatheaceae nor the Schizaeaccae are represented by 

 any well-authenticated Rhaetic species, but in the Palaeozoic genus 

 Senftenbergia we have a still older type which exhibits well-marked 

 Schizaeaceous characters. Klukia exilis agrees precisely as regards 

 the structure of the sporangia with the living members of the 

 family, but in the form of the frond it differs from the modern 

 representatives of the Schizaeaceae. 



The Yorkshire Coast Flora has not so far yielded any recognizable 

 examples of the Gleicheniaceae or the Marattiacese ; species of the 

 former family are known to have existed during the Wealden 

 period, and we have a representative of the latter family in the 

 Rhaetic fern Taniopteris Muensteri. From the Jurassic plant-beds 

 of Poland, Raciborski has described a member of the Harattiaceae 

 under the name Dantea. Neither the Hymenophyllaceae nor the 

 Ophioglossaceae appear to have any representatives among the 

 Inferior Oolite plants. The statement that certain families of fems 

 are not represented, simply means that we have not discovered any 



