270 MESOZOIC FLORAS OF UNITED STATES. 



of these, for which the specific name ellipticum is proposed, was found 

 in a single specimen at locahty No. 4 in the Horsetown beds. This 

 shows the entire leaf, with the exception of the extreme tip. It is 

 small and elliptical in form. It is inequilateral at base, the midrib 

 being there closer to the margin on one side than on the other. The 

 texture of the leaf is thick and firm. A slender midnerve is shown, 

 but the other nervation is indistinct. There are traces of slender nerves 

 that are sent off under a very acute angle and are directed toward the 

 tip of the leaf, as in the Potomac Acacigephyllum. 



Acacia PHYLLUM pachyphyllum Fontaine n. sp. 



PL LXIX, Fig. 19. 



The impression, with its reverse, of a small leaf was found at locality 

 No. 19, in the Knoxville beds. This leaf is remarkably thick and leathery, 

 so as to obscure all its nervation, even the midrib. This thick character, 

 its shape, and its small size make the imprint left by it resemble some- 

 what that of a nut. It is broadly elliptical in form, with the full width 

 maintained nearly to its tip, where it is verj^ obtusely rounded off. It is 

 narrowed gradually to its base, so that it tends to a spatulate form. The 

 midrib is apparently very slender and is not distinctly shown. No 

 other nervation is visible. In form this leaf very much resembles Acacice- 

 phyllum spatulatum Font., of the Potomac beds," but although the 

 texture of that plant is thick, as is characteristic of the Acacisephylla, 

 that of the plant now in question is decidedly thicker. 



GENERAL REMARKS AND CONCLUSIONS. 



This completes the description of all the identifiable plants found 

 in the collections made in the Shasta formation of California and Oregon. 

 The following lists give these plants arranged according to the divisions 

 of the Shasta and Chico formations in which they occur. This grouping 

 will serve to show the distribution of the plants in the formations, and 

 will indicate any changes that took place in ascending from the Knoxville 

 through the Horsetown beds to the base of the Chico, the lower member 

 of the Upper Cretaceous. A reference to the list of localities, with their 

 geological horizons, will show that Nos. 2, 8, and 21 are given as belonging 



a Monogr. U. S. Geol. Surv., Vol. XV, p. 280, pi. cxxxviii, figs. 4, 6-9. 



