4 CRETACEOUS A^^) TERTIARY FLORA. 



if not of actuality. It is thus advisable to look again over what is known 

 to the present time of the characters of the North American Cretaceous 

 flora and to record the deductions legitimately derived from that knowledge. 

 This kind of work is a necessity for the present, as it will be also for the 

 future, not only because what is known now is, probably at least, a mere 

 fraction of the elements constituting the North American Cretaceous flora, 

 but because the determinations of the plants are still and must be for a 

 long time to come unreliable to a certain degree. 



The plants of the Dakota Group, as known mostly by detached leaves, 

 are striking from the beauty, the elegance, the variety of their forms, and 

 from their size. In all this they are fully comparable to those of any geo- 

 logical epoch as well as to those of our time. From entirely developed 

 leaves, less than one inch in size, they show all the gradations of size to 

 one foot, even to a foot and a half in diameter. The multiplicity of forms 

 recognized for a single species is quite as marked as it might be upon any 

 tree of our forests; and to show the admirable elegance of their forms 

 it suffices to say that, at first sight, they forcibly recall those of the most 

 admired species of our time — the Tulip-tree, the Magnolia, the Sassafras, 

 the Sweet-gum, the Plane-tree, the Beech, the Aralia, etc. The leaves of 

 Protopkyllum Sternhergii have the size and the aspect of those of the Catalpa. 

 one of our finest ornamental trees. Those of Menispermites obiusilobus, of 

 Protospermum quadratum, represent in the same manner some of the rarest 

 shrubs, Menispermum, Ferdinandia, etc., carefully raised in conservatories 

 for the graceful forms of their leaves or the richness of their vegetation. 

 It is, indeed, the first impression received from the beauty of forms of the 

 leaves of the North American Cretaceous, and the evident likeness of their 

 fades to that of the finest vegetable types of our time, as we see them around 

 us, which strikes the paleontologist, and may lead him into error in forcing 

 upon the mind the belief of a typical identity where possibly there may be a 

 mere likeness of outlines, a casual similarity of forms in the leaves. For, 

 really, when we enter into a more detailed analysis of these Cretaceous 

 leaves, we are by and by forcibly impressed by the strangeness of the char- 

 acters of some of them, which seem at variance with any of those recognized 

 anywhere in the floras of our time, and unobserved also in those of the 

 geological intermediate periods. Not less surprised are we to see united in 



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