Mr, Clarke's Communication, b^c. 99 



anything which might be assumed to be known to the reader 

 from a study of previous writers j and when_, in former papers^ 

 I vised the identity of the fossil plants of the Indian and Aus- 

 tralian coal-fields as one step in the comparison of the latter 

 with the oolites of Europe,, I was not simply arguing in a 

 circle, as INIr. Clarke seems to suppose, but making use of the 

 knoAvledge published to geologists for more than twenty years 

 that in India these coal plants are accompanied by abundance 

 of ammonites and other marine zoological fossils, haAang the 

 clearest relations with the lower oolitic fossils of the clear 

 sections of Europe. I thus, by a fair philosophic process, 

 transferred to the Australian beds the whole of the geological 

 arguments applied to the identical Indian ones from the 

 association with the latter of those zoological fossils, the ab- 

 sence of which in Australia, Mr. Clarke attempts to use in a 

 powerful manner, but for which I just now indicated an exact 

 parallel in America. Mr. Clarke, in the above paragraph, 

 putting the word " Saffenopteris " in brackets after 

 '' Glossopteris " when speaking of the Indian and Australian 

 plants, proves that he cannot have read Professor PresFs 

 remarks, when founding the genus SagenojJteris, in Sternberg's 

 " Yersuch einer Geognostiscli-botanischen Darstellung der 

 Flora der VorAvelt, " as the very object of establishing the 

 genus was, by separating some abnormal European forms, to 

 leave the Indian and Australian plants as the true types of 

 the genus Glossopteris. Mr, Oldham's quoted statement of 

 Glossopteris occuring in five distinct formations in India, is 

 only intelligible on the supposition that the word " formation " 

 is used — not in the technical sense of geologists, but as synoni- 

 mous -svith "bed." The reference to the occurrence of Glossop- 

 teris in Africa, as supporting the \\e\\ of the palsezoic coal 

 age of the genus, is also imhappy, as the researches of Dr. 

 Rubidge clearly prove that the Glossopteris of Bloemkop, in 

 South Africa, are only found in the Karoo beds containing 

 the bones of the Dicynodon. 



Mr. Clarke's next paragraph states : — " As to Tceniopteris, 

 " so far from determining the age of a formation, Jukes, who 

 " follows Bronn, assigns the species thus : — 



" Carboniferous .... 1"" 



Permian 2 /^ v. /. 



Trias ^>''1:ot7' 



Oolite 6 ' ''°^ ^• 



Tertiary 



ir '> 



?J" 



