GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 303 



in the middle into a short lobe, narrowed upward to an obtuse point, 

 cuneate to the base, with borders undulately denticulate; secondary 

 veins, oblique, straight, the lower pair ascending to the point of the 

 lobes, much divided 5 nervilles, simple, continuous, deeply marked. 



Platanus Heerii, sp, nov. A species represented by many good 

 specimens. Leaves, round in outline, with short, obtuse, lateral lobes, 

 and an obtuse, short point ; borders entire, wavy, or obtusely, distantly 

 dentate, passing in a broad angle, even by a rounded curve toward the 

 petiole, on which they descend in decurring to it, forming a short wing. 

 Petiole apparently short, one inch long, as seen in one of the specimens. 

 The basilar wing is marked with one or two pairs of horizontal, narrow 

 veinlets, running along the borders ; the first pair of secondary veins 

 above them is thick, straight, oblique, much divided in tertiary and 

 quaternary veinlets, which, like the febrilles, are deeply marked. Tex- 

 ture, thick; surface, smooth; areolation of P. occidentalis. As in this 

 species also, the second pair of lateral veins is at a greater distance 

 from the first. 



Sassafras obtusus, sp. nov. A true sassafras, to which is referable 

 the leaf published in Am. Jour. Sci., vol. XLY, p. 94, under the name of 

 Populites SalishuricefoUa, Lsqx. 



Phyllocladus subtntegeifolius, Lsqx., {loc. cit., p. 92.) A larger 

 leaf than the former described ones, obovate, undulate on the borders 

 from the middle upward, obtusely pointed, with same nervation. 



IL— EEMAEKS 01^ THE CEETACEOUS SPECIES DESOEIBED 



ABOVE. 



The above enumeration mentions fourteen species of fossil plants 

 from our Cretaceous formations. It is a small group, indeed ; yet, on 

 the whole, an interesting and valuable contribution to our knowledge 

 of the Cretaceous flora of our continent. Seven of these species are 

 new ; three Fterospermites, the first American representatives of this 

 group, excepting, perhaps, one species of the genus Gredneria, considered 

 by some authors as allied to it, though not yet satisfactorily deter- 

 mined.* The Fterospermites re-appear in the Tertiary of our con- 

 tinent, with analogous characters, at least. P. quadratus, Lsqx., re- 

 sembles, especially by its nervation, P. dentatus^ Heer, from Mackenzie, 

 while P. Haydeni, Lsqx., is, by its size, the form of its leaves, and their 

 nervation, a near relative of P. spectaMlis, Heer, from Greenland. The 

 affinity of typical forms is remarkable, on account of the difference of 

 latitude or of the geograijhical habitat and the geological station of these 

 plants. The fourth new species. Magnolia ensifoUa, Lsqx., is allied by 

 some characters to Magnolia erassifolia, Gopp., from the Tertiary of Sile- 

 sia; while the fifth, the fine Platanus Heerii, Lsqx., has, for represent- 

 ative in our Tertiary, Platanus aceroides, Gopp., and Platanus Guillelmw, 

 Gopp., two intimately related forms. Therefore, on seven new species 

 of the Cretaceous described here, five have a marked Tertiary facies, 

 while, at the same time, three of them, at least, have what may be called an 



* Our Pterosijermites have analogy of form and nervation witli Fierospernnim, Schreb., 

 a genus of the Biittncriacew. Heer, in his Fl. Ter. Helv., has published seeds referable 

 to the same kind" of plants. There is, therefore, scarcely any doubt about the relation 

 of these leaves. It is different with Credneria. Its place is, as yet, undefined. Though 

 resembling by some of its characters, especially by size and* general nervation, the 

 leaves of some Ptei-ospermites, their form, their i)asi'lar nervation, and the mode of at- 

 tachment of the petiole are different. We have from our Cretaceous of Nebraska one 

 Credneria, (C. ie cojiteai? a, Lsqx.,) apparently identical with C. inacro2)hylla, Heer, of the 

 Quadersandstein or Upper Cretaceous of Moleteiu, Moravia. 



