144 CONTRIBUTIONS TO PAL^ONTOLOGY 



The collections contain 6 impressions of cordate-orbicular leaves which differ only in an 

 additional pair of secondaries along the midrib from the type and figured specimen of Menisper- 

 mites knightii. The original description was as follows: 



"Leaf evidently thick in texture, broadly cordate, with roundcd base and verj' deep sinusesi 

 rounded, truncate at apex; margin undulate lobed, thc lobes very short, obtuse, and entire or 

 erose; nervation pahnate, with about sevcn primary nerves of equal strength which apparently 

 pass to the roundcd lobes or are once or twice forked, the branches passing to the lobes; finer 

 nervation not preserved." 



The obscrvablc characters of this leaf form resemble those of several menispermaceous genera, 

 particularl.y Cocculus. On the other hand, the thick texture is suggestive of an aquatic leaf. 

 Among aquatic genera there is a marked resemblancc to several of the Nj-mpha^acese, particularly 

 Castalia {Nympbsea). These differ, however, in minor respects, mainly in their more numerous 

 secondaries and in their deeply cordate bases. In the absence of better comparison with modern 

 leaves, it seems advisable to retain the more gencral name applied by Knowlton. 



This species is at present known only from the Lance formation and the Mesaverde formation 

 of southeastern AVyoming. 



Occurrence — Locality P3858. 



Collection—lJ. C. Mus. Pal., Plesiotype No. 252L 



Family MAGNOLIACE^ 



Genus MAGNOLIOPHYLLUM Conwentz 



Magnoliophyllum cordatum Dorf 



Magnoliophyllum cordalum Dorf, Carnegie Inst. Wash. Pub. No. 508, pt. I, 64, pl. 9, fig. 5, pl. 10, fig. 1, 1938; 

 BuU. Geol. Soc. Amer., vol. 51, 218, 222, 225, 1940. 



This species is not abundant in the collections. Only 4 specimens of incomplete, though 

 well-preserved, leaves were encountered. The general .shape, the cordate base, and the prominent 

 secondaries with pronounced marginal loops are sufficientlj' well shown, however, to permit the 

 determination without hcsitation. 



I have not as yet cncountercd spccimens or figures of prcviously rcported leaves of this form 

 in the Cretaceous or early Tertiary floras, aside from those of the Medicine Bow flora. The re- 

 semblancc of thcse forms to the leaves of the Magnoliacese has already been discussed in the 

 original description of this species. 



Occurrence — Localities P3855, P3857. 



Collection—\5 . C. Mus. Pal., No. 2522. 



Family ANACARDIACEJE 



Genus PISTACIA Linn6 



Pistacia eriensis Knowlton 



(Plate ll.Figs. 1,3) 



Pistacia ericTUfis Knowlton, V. 8. Gcol. Surv. Prof. Paper 130, 150, pl. 28, figs. 1-4, 1922. Dorf, Carnegie 

 Inst. Wash. Pub. No. 5as, pt. I, 65, pl. 19, fig. 7, 1938; HuII. Gcol. Sor. Amer., vol. 51, 21S, 222, 225, 1940. 

 Pistacia hoUicki Knowlton, U. S. Geol. Surv. Prof. Paper 130, 151, pl. 28, figs. 5, 6, 1922. 



Therc are 3 specimcns, from two localities, which cannot be distinguished from any of the 

 various type and figured specimcns of this species froni the Medicinc Bow and Laramie formations. 



Both the fo.ssil and modcrn relationships of this species have already been adequatelj' dis- 

 cussed in the reports citcd abovc. 



Occurrence — Localities P3651, P3859. 



Colleclion—V. C. Mus. Pal., Plesiotypes Nos. 2523, 2524. 



