FOSSIL VASCULAR CRYPTOGAMS 



121 



discovered that cannot be referred to some existing type. The preva- 

 lent forms appear to have been the Polypodiacege, HymenophyllaceEe, 

 and Marattiacefe ; this last order having been apparently much more 

 widely distributed and more abundant in the earher periods than it is 

 now. 



The HYMENOPHYLLACEyE may possibly have been one of the earliest 

 differentiated types. In Palaeopteris hibernica (Schmp.) (Cyclopteris 



;. — A, frond of Palceopteris hibernica Schmp. (restored) (-^-6) ; B, pinnule (somewhat mag.) ; 

 ■tile pinna (nat. size) ; D, two cup-shaped indusia attached to the filiform midrib (mag.) ; E, 



Fig. Q3. 

 sporanges of a hymenophyllaceous fern from the coal measures (mag.). (After Carruthers.) 



hibernica, Forbes), specimens have been found in which all the lower 

 pinnae are fertile. The pinnule was reduced to a midrib supporting the 

 slender stalks of the bilabiate cup-shaped indusia ; and the stalk is con- 

 tinued into the indusium, to which the sessile sporanges are attached. 

 The texture of the frond was not membranaceous, like that of most exist- 

 ing Hymenophyllaceae, but was more like that of Loxsoma. On the 

 rachis between the pinnae are seated single large decurrent pinnules. 



