1504 



C0RM0PHYTA. 



into several subfamilies. The sporangia are very numerous, and 

 are borne on the underside of usually unmodified leaves ; and 

 they split transversely. Of the subfamilies, the Polypodiece 

 are perhaps represented by the typical Polypodium in the Mio- 

 cene of Switzerland ; Chi- 

 lanthes occurs in the same 

 deposits ; while the widely- 

 spread Pteris (Bracken) is 

 found abundantly in the 

 Upper Cretaceous and the 

 Middle and Upper Tertiaries 

 of Europe, and also in the 

 Laramie and Tertiaries of 

 America. Adiantum is also 

 equally well represented 

 throughout the European 

 Tertiaries, and if we include 

 in it the so-called Adiantites, 

 it ranged down to the Ju- 

 rassic. In the Aspleniece, 

 Blechnum (Hard-fern), distin- 

 guished by having both fertile 

 and sterile leaves, of which 

 the latter are simply pinnate, 

 occurs in the Continental 

 Eocene and Miocene. Cu- 

 riously enough, the South 

 American genus Hewardia 

 is found in the Upper Eo- 

 cene of Bournmouth. Wood- 

 wardia, now represented by 

 eight species from the warmer 

 regions of the world, occurs 

 in the Pliocene and Miocene of Europe, the species from the for- 

 mer, and perhaps also that from the latter, horizon being identical 

 with an existing type ; this genus also occurs in the Miocene of 

 the United States. Asplenium, which at the present day numbers 

 some 300 species, occurs commonly throughout the European Ter- 

 tiaries, and is also found in the Cretaceous ; some of the species 

 being allied to existing European forms, while others are more 

 nearly related to those of the tropics. It appears, moreover, that 

 Ferns from the Jurassic of Siberia and the Jurassic and Rhaetic of 

 Europe, described under the name of Cladophlebis and Alethopteris, 

 are referable to this genus. Ferns of this genus also occur in the 

 English Wealden ; in both the Lower (Damuda) and Upper (Raj- 



Fig. 1368. — Lateral branches of the leaves of 

 Thrysopteris Murrayana; from the Inferior Oolite 

 of Yorkshire. Enlarged leaflets, with sori, are 

 shown in the lower figure. 



