308 CONCLUSION. 



rhoifolia and S. Gocppertiana and on the other with the smaller 

 "Wealdcn type S. Mantelli. 



In the case of the abundant and handsome fern Cladophlelm 

 denticulata we lack convincing evidence of family relationship, but 

 such indications of soral characters as occur point to a polypodiaceous- 

 affinity. The bipinnatc form of frond of this species is practically 

 identical with that of certain Rhaetic ferns, e.g. Cladophkh's 

 Roesserti, and with ferns of "Wealdcn age, e.g. C. Albertsi. Ferns 

 of the Cladophkh's denticulata type are very abundant in Mesozoie 

 strata, but in most cases we are unable to determine their systematic 

 position ; this form of frond is in itself of little or no use as an 

 aid to the recognition of botanical relationship. 



As Nathorst has stated, it is not improbable that some of the 

 Bphenopteroid fronds from the Inferior Oolite rocks may be best 

 compared with species of the recent Polypodiaceous genus Bavallia. 



Passing from these rather doubtful examples of Jurassic 

 Polypodiaceae, we may turn to other more satisfactory fern species. 

 It is clear that the Matonineae played a prominent part in the 

 vegetation of the Oolitic period ; Matonidium Goepperti and the 

 two species of Laccopteris, L. polypodioides and L. Woodwardi, are 

 fairly abundantly represented by well-preserved fertile specimens. 

 This interesting family, with two surviving species in the Malayan 

 region, occupied an even more prominent position in the Rhaetic- 

 than in the Jurassic period. From Bhaetic times, when the family 

 appears to have reached its maximum development, the Matonineae 

 gradually decrease in importance, and at the present day the genus- 

 Matonia alone remains as a survival from Mesozoie times. 



Bipteridinm. This family, treated as a subdivision distinct from 

 the Polypodiaceae for reasons already discussed, 1 appears to have 

 a geological history similar to that of the Matonineae. Bictyo- 

 phyllum rugosum, one of the more abundant of Inferior Oolite types, 

 is practically indistinguishable from B. JVilssoni, B. acutilobum, and 

 other Rhaetic species. The genera Camptopteris and Clathropteris 

 afford other Rhaetic examples of the same family, and in the 

 "Wealdcn flora we have the genus Protorhipis, which approaches 

 most closely to the surviving fern Biptcris, another tropical 

 remnant of a Mesozoie family. 



1 Ante, p. 119. 



