326 GEOLOGICAL SURVEY OF THE TERRITORIES. 



similar to those of P. aceroides, of tbe Miocene, that I was at first 

 disposed to consider them as identical ; then, F. Heerii, rare, like the 

 former, and found as yet only along the bluffs of the Sa.lina River ; P. 

 oMusiloba, from a number of somewhat fragmentary specimens from 

 Beatrice, ^Nebraska, all representing leaves of about the same size and 

 of the same characters ', P. affinis, P. recurvata, and P. diminutiva. All 

 the species are described and figured in Cretaceous Flora. The last one 

 as remarked in its description may be a dwarfed form of P. primmva or 

 P. Seerii. The- leaf appears as gnawed along the veins by insects or 

 perhaps by a parasite fungus. Its specification is not positive and is 

 subject to criticisms. The base of the leaf is rounded to the petiole, 

 a character as yet unique for a species of this kind. P. recurvata 

 should, following the opinion of my honored friend Count Saporta, be 

 referred to the Aralicese by a more intimate afiinity to Araliopsis 

 species ; and Platanus affinis seems now, after the examination and 

 comparison of a number of specimens from Kansas, more evidently 

 referable to the Ampelidece than to the Platanew. Therefore these two 

 last species are now eliminated from this generic division. I persist in 

 considering P. Heerii and PL obttisiloba as two different species, though it 

 has been suggested that the last was probablj' a mere variety of the 

 first. The identity is denied not only by the facies, and the nervation 

 of the leaves, but especially by the thinner texture of those of P. 

 ohtusiloha. The fact, that the numerous specimens representing it are 

 all from the same place in Nebraska, and that P. Heerii has not been 

 found in this State till now, confirms this separation. In regard to this 

 last species, Professor Geinitz has remarked in the Isis, 3875, p. 558, 

 that paleontologists might perhaps recognize in it a Credneria. There 

 is some similarity in the general outline of the leaves, indeed. But this 

 might be said of many of the generic forms of the Cretaceous, which seem 

 to refer to a few different types, or to present in one leaf the characters 

 which we now generally find isolated in separate vegetable groups. 

 The genus Credneria, known as it is to me by what is described in the 

 vol. V, of the Paleontographica, by Stiehler, includes species with cord- 

 ate or subcordate leaves (none narrowed to the petiole), and bearing 

 above the base two or three true secondary veins in right angle to the 

 midrib. In P. Heerii, the leaves are cuneate to tbe base, even gradually 

 narrowed or decurrent to the petiole, which thus becomes slightly winged, 

 and the veins under the primary nerves are mere marginal veinlets. Per- 

 haps the relation of this species is more marked to the genus JStting- 

 hausenia, which, I regret to say, is scarcely known to me except by 

 Chondrophyllum grandidentatum, as represented by Heer in the Creta- 

 ceous Flora of Moletin, and by PhylUtes repandus, Sternb., two forms 

 which have no afiinity to Platanus. 



In regard to its geological distribution, this genus is truly remark- 

 able. No trace of it is recorded as yet in the Cretaceous of Europe, not 

 even in the Paleoceue and Eocene of France, so rich in fossil vegetable 

 remains. Its first appearance in Europe is in the Upper Miocene of 

 Oeningen, and of Austria and Italy, where it is represented by two 

 very similar forms, Platanus Guillehnce and P. aceroides. These two 

 species are present in the same lormation from the northern parts of the 

 Arctic lands to Italy. It is followed in the Upper Tertiary or Pliocene 

 of this last country by Platanus Academice Gaud, related as originator, 

 perhaps, to the living P. orientalis. I have remarked above that the 

 relation of leaves of the Dakota group to Platanus has been considered 

 as doubtful by some European paleontologists. This doubt may have 

 been induced by the understanding of the total absence of Platanus 

 leaves in the Cretaceous and Lower Tertiary of Europe. If so, it is cer- 



