Vol. 59.] OCCUKRENCE OF DICTYOZ AMITE8 IN ENGLAND. 227 



Oolite ; the plants described by Prof. Nathorst and in a later paper l 

 by Dr. Yokoyama were obtained from different localities, and pro- 

 bably belong to an uppermost Jurassic and Lower Cretaceous horizon. 

 As regards the later floras, which contain several Wealden species, it 

 is of interest to note the absence of Weichselia Mantelli (Brongn.), 

 a species abundantly represented in the Wealden vegetation of 

 Europe. 2 



India. 



The Rajmahal Series of India, with which alone we are imme- 

 diately concerned, contains, as Feistmantel pointed out, several 

 forms which bear a close resemblance to types of Rheetic age, and 

 there can be little doubt that this flora should be referred to a 

 somewhat lower horizon than the Inferior-Oolite flora of England. 

 In spite of its slightly more ancient facies, the Indian flora, as a 

 whole, exhibits a close agreement in its composition with that of 

 Yorkshire. 



In the foregoing lists I have substituted the generic name 

 Williamsonia for certain pinnate fronds from the B-ajmahal Series, 

 which it has been the general custom to include in Morris's genus 

 Ptilophyllum. The use of the latter term, as one denoting Cycadean 

 fronds peculiar to Indian floras and distinguished, by the manner of 

 attachment and arrangement of the pinnae, from European leaves of 

 similar habit, has been one cause of exaggerating the differences 

 between Indian and Western floras. Feistmantel, in his paper of 

 1876, 3 speaks of Ptilophyllum, like Dicti/ozamites, as an Indian 

 genus, and the practice has been to regard species so named as 

 essentially distinct from European types. In the British Museum 

 Catalogue published in 1900, 4 I expressed the view that there is 

 no difference, between the abundant fronds from the Inferior Oolite 

 of Yorkshire formerly known as Pterophyllum pecten, L. & H., and 

 certain Indian species referred to Ptilophyllum. This conclusion 

 is based on the examination of several specimens of the Indian 

 fronds and their comparison with the English forms. Ptilophyllum 

 cutchense and Pt. acutifolium of Feistmantel appear to me, not 

 merely generically but specifically, identical with the English 

 species, and this opinion derives support from the association of 

 both the Indian and English leaves with specimens of reproductive 

 structures of the Williamsonia-tyipe. There is no need to re- 

 capitulate the facts bearing on the probable connection between the 

 small form of Williamsonia, named by Prof. Nathorst W. Leckenbyi, 5 

 and the fronds of Pterophyllum pecten, L. & H. ; a conclusion arrived 

 at by Mr. Carruthers in 1870,° and adopted by several authors. This 

 question, as well as a fuller comparison of the Indian and European 



1 Yokoyama (95). 2 Seward (94) & (00 2 ). 



3 Feistmantel (76) p. 5. * Seward (00 3 ) p. 192. 



3 Nathorst (80). ° Carruthers (70) p. 694. 



