COIflOPTEEIS. 103 



Coniopteris hymenophylloides. 1 The fragment drawn by Williamson 

 in pi. clxviii. of the Fossil Flora* is precisely similar to the 

 specimens represented in PL XX. Fig. 1 and in PL XVI. Fig. 4. 



In the third edition of Phillips' Geology of Yorkshire there are 

 portions of various Sphenopteroid fronds figured under several 

 specific names, but in many cases the drawings are not accurate 

 enough to render possible the recognition of the type-specimens. 

 Some of the species of Sphenopteris instituted in Phillips' work 

 are no doubt identical with C. hymenophylloides : of these may be 

 mentioned S. affinis, agreeing with PL XX. Fig. 2 ; also S. socialis 

 and 8. dissocialis. It is clear that the fertile pinnae of the form 

 originally named by Lindley & Hutton Tympanophora, and 

 compared by them to an alga, are of the same type as we now 

 find among Cyatheaceous ferns, the sori being partially enclosed by 

 a cup-shaped indusium and consisting of several sporangia with 

 an obliquely vertical annulus. It has been the custom of many 

 authors to consider this Tympanophora form of fertile pinna closely 

 allied to, or identical with, Kunze's recent species of the monotypic 

 genus Thyrsopteris, now confined to Juan Fernandez. The use 

 of this generic name has, however, been much too widely used by 

 palaeobotanical writers. I have elsewhere drawn attention to the 

 obvious misuse of this generic name by Fontaine in his Potomac 

 Flora. 3 Other writers have adopted, to a less degree, the same 

 misleading use of this genus. It is true that some of the examples 

 of fertile pinnae from the Lower Oolitic rocks are practically 

 identical with those of Thyrsopteris elegam and are in all proba- 

 bility very near allies of this recent species, but we find precisely 

 similar fertile pinnae in other genera of recent Cyatheaceao as in 

 the species Dicksonia Bertervana, Hook., represented in Text-fig. 13. 

 In this species the lamina of the fertile segments is considerably 

 reduced, and the indusium consists of a cup with two lips; this 

 two-lipped form of the indusium is not a character easy to recognize 

 in a fossil specimen, nor is it by any means very obvious in dried 

 examples of recent fronds. 



There is the question of the identity of various types of 

 fertile pinnae met with in association with sterile pinnules of 



1 Seward (00), p. 7. 



2 Lindley & Hutton (35), pi. ckviii. 



3 Seward (94), p. 45. 



