LANCE FLORA OF EASTERN WYOMING 155 



Rhamnus? minutus Knowlton 



(Plate 17, Fig. 12) 



Rhamnus minutus Knowlton, U. S. Geol. Surv. BuU. 696, 548, 1919; U. S. Geol. Surv. Prof. Paper 130, 155, 

 pl. 17, fig. 2, 1922. Dorf, BuU. Geol. Soc. Amer., vol. 51, 218, 222, 225, 1940. 



There are 3 nearly complete specimens of small, linear, coriaceous leaves which are similar 

 in essential details to the type and figured specimen of this Laramie species. Its resemblance to 

 Rhamnus salicifolius Lesquereux ' has been pointed out by Knowlton, who noted, however, the 

 difference from that species in margin and tertiary venation. No other comparable leaves have 

 come to my attention. 



Although I can suggest no alternative, the generic reference of this species to Rhamnus is 

 open to question. I have seen no leaves of existing species of Rhamnus which are comparable in 

 observable details. 



OccMrrence— Localities P3857, P3859. 



Collection—V. C. Mus. Pal., Plesiotype No. 2564. 



Trapa? niicrophylla Lesquereux 



(Plate 17, Figs. 1, 2, 6) 



Trapa'! microphylla Lesquereux, U. S. Geol. and Geog. Surv. Terr., Bull., vol. 1 (1875), 369, 1876; U. S. Geol. 

 and Geog. Surv. Terr., Ann. Rept. (1874), 304, 1876; Rept U. S. Geol. Surv. Terr., vol. 7, 295, pl. 61, 

 figs. 16-17a, 1878. Ward, U. S. Geol. Surv. 6th Ann. Rept., 554, pl. 49, figs. 2-5, 1885; U. S. Geol. Surv. 

 Bull. 37, 64, pl. 28, figs. 2-5, 1887. Knowlton, U. S. Geol. Surv. Mon. 32, pt. 2, 661, pl. 77, figs. 3, 4, 

 1898; U. S. Geol. Surv. BuU. 163, 62, pl. 5, fig. 7, 1900; U. S. Geol. Surv. Bull. 257, 144, 1905; Proc. Wash- 

 ington Acad. Sci., vol. 11, 189, 202, 207, 1909. Berry, Canada Geol. Surv. Mem. 182, 61, pl. 19, figs. 1-11, 

 1935. Brown and Houldsworth, Jour. Washington Acad. Sci., vol. 29, no. 1, 36, 1939. Dorf, Bull. Geol. 

 Soc. Amer., vol. 51, 218, 220, 222, 225, 226, 229, 1940. 



There are 35 well-preserved, detached leaflets, from five localities, which cannot be dis- 

 tinguished from the type and figured specimens of this widespread species. Knowlton has pre- 

 viously reported this species f rom the Lance Creek area ; ^ I have seen his excellent specimens in 

 the collections at the U. S. National Museum (specimens No. 1003 [1462]). 



Both Berry and Brown have discussed the uncertain systematic status of this species and 

 have fully described its well-defined characters. Leaflets of this form are widespread and abun- 

 dant in rocks of both Late Cretaceous and Paleocene age in the Rocky Mountain region. 



Occwrrence— Localities P3853, P3854, P3856, P3858; U. S. Geol. Survey Locality 1462. 



Colledion—\J. C. Mus. Pal., Plesiotypes Nos. 2565, 2566, 2567; Nos. 2568, 2569, 2570. 



Phyllites trifoliatus Dorf, n. sp. 

 (Plate 17, Figs. 3, 4) 

 LysinMchia sp., Knowlton, Proc. Washington Acad. Sci., vol. 11, 207, 1909. 



There is a single specimen and counterpart, borrowed from the U. S. National Museum, 

 which is unUke anything else seen in the collections. There are, moreover, no fossil species in 

 either Cretaceous or Tertiary floras with which the specimen can be compared. 



Description — Leaves apparently arranged in trifoliate manner; individual leaflets broadly 

 ovate to eUiptic, 1.8-3.9 cm. long by 1-1.5 cm. wide; margins entire; bases and tips acutely wedge- 

 shaped; venation pinnate with 4-6 pairs of subopposite secondaries, coming off the raidribs at 

 acute angles and arching sharply upward, becoming essentially parallel to the midribs at their 

 distal ends; tertiary venation very fine, indistinct; texture apparently fairly thick. 



I have been unable to find any modern leaves which resemble this species. It may be that 

 the trifoliate arrangement is more apparent than real, so that the leaflets are actually a whorl of 

 spirally arranged leaves of a type seen, for example, in various members of the family Primulacese. 

 Until better specimens of this species are obtained, however, it seems best not to make a definite 

 generic assignment. 



' Lesquereux, L., Rept. U. S. Geol. Surv. Terr., vol. 7, 282, pl. 53, figa. 9, 10, 1878. 

 ' Knowlton, F. H., Proe. Washington Acad. Sci., vol. 11, 207, 1909. 



