LESQ0EEEUX.] PALEONTOLOGY LIGNITIC FLORA — SPECIES. 419 



rootlets, cuning to an horizontal direction! Though the specimens 

 representing this species are very numerous and very large, I could not 

 obtain one showing exactly the size and the form of these leaves. They 

 appear either folded around a thick stem, from which they diverge, or 

 on both sides of a thick rachis extending along it like wings,*^ two to three 

 centimeters wide on each side. From the fact that large specimens are 

 covered by fragments of these leaves crushed and folded upon another, 

 without any trace of middle nerves or peduncles, the leaves must have 

 been of great size. Their sabstauce is not very thin. The surface is per- 

 place covered with an epidermis which shows the veins as crossed by 

 veinlets at right angle. When the epidermis is destroyed, this charac- 

 ter is not observable; it may, therefore, result of a wrinkling of the epi- 

 dermis. The species is related to 31usa Bilinica, Ett., (Bil. Fl. p. 28, PL 

 vi. Fig. 11, and PI. vii. Figs. 4-5 ;) differing, however, by essential char- 

 acters. 

 Habitat. — Eoof-shale of a thin coal, with the following species : 



Sapindus obtusifolius, sp. nov. 



Leaves compound, pinnate, apparently long ,• leaflets alternate, very 

 variable in size, from li to 7 centimeters long, and from 6 milli- 

 meters to 3^ centimeters broad, coriaceous, perfectly entire, sessile, un- 

 equilateral, ovate-lanceolate, obtusely-pointed ; nervation camptodrome ; 

 lateral veins at a broad angle of divergence, curving in passing up to the 

 borders and following close along them by a series of undulations ; 

 areas large, equilateral 5 ultimate divisions obsolete. This fine species 

 differs from any fossil published as yet. The leaves have been appar- 

 ently very large ; some of the detached leaflets greatly differing in size 

 from the few ones which were obtained still attached to the main rachis or 

 pedicel. 



Habitat. — The same locality as the former ; top of hills, apparently 

 overlying the coal-bearing strata of Eock Springs, seen to the east, 

 five to six miles distant. The clay beds of this locality, with an 

 abundance of silicified and petrified wood, the thinness and poor quality 

 of the lignite beds, mark this place as referable to the Upper Lignitic 

 measures. Though I worked at the locality for an entire day with a miner, 

 I could not find in the shale any other distinct vegetable remains but 

 the two species described here. As yet, we have nothing related to 

 them from the lower lignitic flora. 



§4.— CLIMATE OF THE AMEEICAK TEETIAEY AS EEPEE- 

 SENTED m ITS FLOEA. 



That the flora of a country is in correlation to local atmospheric cir- 

 cumstances; that ancient floras, too, bear characters which relate to the 

 same cause, is an axiomatic assertion which does not need any discus- 

 sion. In considering the development of vegetable types from the first 

 apparition of land-plants, as far as this origin is known, it has been ad- 

 mitted also that the point of departure of the vegetation has been from the 

 simplest organisms, passing up to more and more complex ones in as- 

 cending the series of the formations. According to this principle, the 

 first reyjresentatives of dicotyledonous plants, which seem to have made 

 their appearance near the base of the Cretaceous, but which have not 

 been remarked as yet,* have been theoretically considered as being of a 



* Professor Heer has, from the Lower Cretaceous of Greealand, a loaf resembling a 

 Popiilus, mixed still with Jurassic or Wealdeu types. 



