482 REPORT UNITED STATES GEOLOGICAL SURVEY. 



many, that I do not see as yet any cliaracters to authorize a specific dis- 

 tinction. Tlie American leaves are somewhat larger, with broader lobes, 

 the middle one longer than the lateral ones. In Heer's species, the mid- 

 dle lobe is shorter, bat there is no other apparent difference, the nerva- 

 tion being the same, and the borders of the leaves crenulate in exactly 

 the same manner. By the leaves, therefore, we have proof of the geo- 

 logical relation of the Dakota Group with the Cretaceous strata exposed 

 at the base of the Rocky Mountains, and also of the Cretaceous of Colo- 

 rado with that of Europe. The Moletin formations, according to Heer, 

 represent the Lower Quadersa7idstein, a stage generally named now 

 Ceiiomanian, which is overlaid by the Thuronian, the Cfpper Quader, and 

 this by the Planer of Eeuss, now the Senonian.^ 



This relation of our Dakota Group flora with that of Moletin had been 

 remarked already by the presence, in both formations, of Sequoia fasti- 

 giata, Sequoia BeichenhacM, Glelclienia Kurriana, and Pinus Quenstedti, 

 species described in the Annual Eeport of 1874. But the identifica- 

 tion of dicotyledonous is, in regard to the age of the formation, of 

 a more definite character than that of Ferns and Conifers. And still in 

 the same specimens of Colorado we have other leaves apparently, thougli 

 less positively, referable to species of Moletin. One of them has the 

 same form and the same character of nervation as the fragment figured 

 by Heer as Myrtrophylhini tSMlhleri, pi. xi, fig. 2, loc. cit., which is, how- 

 ever, half of a leaf, whose lower and upper parts are destroyed. Others 

 represent Magnolia of the same type as HI. speciosa, Heer, and there is, 

 besides, a cylindrical obtuse receptacle, four centimeters long, a little 

 more than one centimeter broad or thick, covered with numerous imbri- 

 cated carpels, much like the receptacles of the living Magnolia grandi- 

 folia, and comparable, in its unripe state, to a fruit of Magnolia figured 

 by Heer, pi. viii, fig. 2, as ill. ampHfoUa. Other and numerous leaves, 

 related by their shape and nervation to Magnolia alternans, Heer, of the 

 Dakota Group, are somewhat unequal at the base, attached on both 

 sides of a pedicel, and therefore mere leaflets of compound leaves. 

 These, and still others of a different character of nervation, with leaf- 

 lets more unequal at the base, resembling large species of Sapindus, seem 

 referable to Leguminosw, as a large silique, like that of a Lonchocarpus, 

 is seen upon the same specimens. 



The most interesting new type of these Cretaceous i)lants is described 

 under a new generic name, that of Liriojyhi/llum, by reason of its affinity 

 to leaves of Liriodendron. These leaves belong probably to two spe- 

 cies. The largest, that of Liriopliyllum Bechicithii, sp. nov., are square 

 in outline, divided into two lobes on each side, measuring about 30 centi- 

 meters between the points of the lateral lobes, 20 centimeters from the 

 top of the petiole to that of the oblique obtuse terminal lobes, which 

 descend to near the base where the midrib is split in two, each of the 

 branches, under an angle of division of 45°, ascending to the points of 

 the two upper lobes. There is still a nearly basilar pair of strong sec- 

 ondary nerves curving backward, and passing through the middle to 

 the point of the lateral lobes, with two other secondary nerves, one 

 merely marginal, the other between the two pairs forming the division 

 of the leaves ; the secondary nerves are scarcely branching ; the lower 

 part of the midrib, below the slightly obtuse sinus of the middle lobes, 

 is thick, 3 millimeters, and passes downward to a petiole of the same 

 size, broken 2 centimeters lower than the somewhat decurving base of 

 the leaves. 



The other species as yet considered under the name of Liriophyllum 



* Heer, Moletin Flora, p. 5. 



