FOSSIL VASCULAR CRYPTOGAMS 121 



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

 lent forms appear to have been the Polypodiacese, Hymenophyllaceae, 

 and Marattiacese ; this last order having been apparently much more 

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

 now. 



The KtYMENOPHYLLACE^ may possibly have been one of the earliest 

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



Fig. gs. — A, frond of PaleEopteris hibernica Schmp. (restored) (-^6) ; B, pinnule (somewhat mag.) : 

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

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



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

 pinnse 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 Hymenophyllacese, but was more like that of Loxsoma. On the 

 rachis between the pinnae are seated- single large • decurrent pinnules. 



