FOSSIL ANGrOSPERMS 273 



been, and as the Dicotyledons now are, although they do not 

 seem to be so abundant now as they were during the Tertiary. 

 When they do appear in undoubted forms, they are almost com- 

 pletely differentiated and widely distributed. Their ancestral 

 forms are obscured in the maze of unintelligible forms that pre- 

 cede them. The only suggestion of paleobotany as to the origin 

 of the Monocotyledons is that they are certainly a younger type 

 than the Gymnosperms. 



Rejecting the claim for Carboniferous Monocotyledons, we 

 encounter one for their existence during the Jurassic. This 

 rests upon the occurrence of certain forms of grass-like habit, 

 which suggest Monocotyledons, but such evidence can not be 

 accepted as conclusive. There is certainly no clear proof of the 

 existence of Monocotyledons in any strata earlier than the Cre- 

 taceous.* 



The probability of Monocotyledons during the Jurassic rests 

 not upon positive discovery, but upon the fact that during the 

 Cretaceous they were abundant everywhere, and give evidence 

 of their long presence. The earliest history of the group, 

 therefore, is an absolute blank, and we are introduced to it in 

 an advanced stage of development. 



The record can be considered under three general catego- 

 ries — namely, (1) those families represented during the Cre- 

 taceous, (2) those whose earliest representatives are in the Ter- 

 tiary, and (3) those only known since the Tertiary. It must 

 be observed that the second and third categories are based upon 

 negative evidence — that is, representatives of these families 

 have not been found as yet at any earlier period. It must also 

 be remembered that many plants have a habitat and structure 

 unfavorable to their preservation as fossils, so that failure to 

 discover them in the geological series is no positive evidence 

 that they did not exist. With the uncertainties understood it 

 may be safe to present such evidence as we have. 



Cretaceous Families. — There seems to be sure evidence 

 of the existence of five families during the Cretaceous, and a 

 possibility of the occurrence of a sixth. 



The Pandanaceae were present and were widely distrib- 



* See Seward, A. C. : Notes on the Geological History of Monocotyledons. 

 Annals of Botany 10: 205-220. pi. 14. 1896. 



