162 CONCLUSION. 



of various local floras, we shall inevitably exaggerate the differences 

 in their composition by adopting the nomeiiclature used by 

 individual authors. "We must seek to discover whether types 

 recorded from one region are represented by similar types in other 

 parts of the world ; it is of less importance to endeavour to decide 

 if a southern hemisphere plant should be regarded as specifically ' 

 identical with a northern form than to discover in what degree the 

 general facies of an Eui'opean flora is repeated in a flora from 

 southern latitudes. In the following list I have therefore 

 adopted a liberal interpretation of specific designations, and have 

 endeavoured to show to what extent representative or identical 

 types occurred in various parts of the world during the Ehsetic and 

 Jurassic eras. In taking considerable liberties with the nomen- 

 clature of other authors, I do not necessarily mean to express 

 disagreement with them as regards their interpretation of affinity ; 

 but my aim is to avoid the danger of allowing slight differences — 

 whether of specific rank or not — to obscure the broad relationships 

 of floras. The method of comparison is adopted primarily for the 

 purpose of instituting a botanical comparison, rather than with the 

 view of expressing an opinion as to the relative age or strati- 

 graphical position of the rock.' 



In the following table (pp. 164-167) I have indicated, in the 

 case of the Oolitic species, the sub-stages from which the fossils 

 have been obtained. 1.0. = Inferior Oolite ; G. 0. = Great Oolite ; 

 Cor. = CoralHan ; Oxf . = Oxfordian ; Kim. = Kimeridgian. 



Eh^tic. — The English Ehsetic species constitute too meagre 

 a sample of a Ehaetic flora to render necessary any discussion as to 

 the distribution and composition of the Ehsetic vegetation. The 

 wide range of Equisetites Mumsteri and allied forms and of the 

 fern Clathropteris may be taken as an index of the uniformity of 

 Ehsetic floras throughout the world. In addition to the countries 

 named in the table Chili ^ and Honduras may be mentioned as two 

 other regions from which Ehsetic plants have been recorded. 

 Newberry has drawn attention to the uniformity of the Ehsetic 



1 Seward (03). 



^ Sohns-Lauljach (99). 



