100 



LARAMIE FLORA OF THE DENVER BASIN. 



been found in beds above the unconformity. 

 Rhamnus saliciformis was described originally 

 from specimens obtained in the Laramie and 

 has subsequently been found in the Montana 

 at a number of horizons. The two species of 

 Ficus are well-marked forms and probably 

 have been correctly identified in both areas. 



In addition to the flora of the Vermejo, 

 which is of course of Montana age, it may- be of 

 interest to compare the Laramie flora with the 

 Montana flora as a whole. The following 

 species are common to the two : 



Anemia elongata (Newberry). 



?Anemia Bupercretacea Hollick. 



Sequoia reiehenbachi (Geinitz) Heer. 



Sequoia longifolia (Lesquereux) Knowlton. 



Sabal montana Knowlton. , 



Myrica torreyi Lesquereux. 



Fiqus dalmsttica Ettingshausen. 



Ficus praetrinervis Knowlton. 



Ficus planicostata Lesquereux. 



Rhamnus salicifolius Lesquereux. 



In addition to the species that are regarded 

 as actually identical in the Laramie and Mon- 

 tana floras, there are two that are obviously 

 related to Montana species, as follows : 



Palaeoaster? similis, aff. P. inquirenda. 

 Artocarpus liriodendroides, aff. A. dissecta. 



RELATIONS TO THE "LOWER LARAMIE" OF 

 CARBON COUNTY, WYO. 



One of the most interesting results brought 

 out by this study is the close relation that is 

 shown to exist between the flora of the Laramie 

 in the Denver Basin and the flora of the so- 

 called "Lower Laramie" (now the Medicine 

 Bow formation) of Carbon County, Wyo., and 

 adjacent areas. The flora of the "Lower Lar- 

 amie" at present known is confined in the main 

 to the lower 300 or 400 feet of beds, and though 

 it has not yet been fully exploited, the follow- 

 ing forms at least are known to occur : 



Apeibopsis discolor Lesquereux. 



Aristolochia sp. 

 *Artocarpus lessigii (Lesquereux) Knowlton. 



Carpites sp. ' 



*Cassia marshallensis Knowlton. 



Ceanothus? sp. 

 *Cinnamomum affine Lesquereux. 

 *Oyperacites sp.? 



Daphnogene elegans Watelet. 



Diospyros? ficoidea Lesquereux. 

 *Dombeyopsis obtusa Lesquereux. 

 *Dombeyopsis trivialis Lesquereux. 



Dryophyllum cf. D. aquamarum Ward. 



Dryophyllum bruneri Ward. 



*Dryopteris carbonensis Knowlton. 



Equisetum, tubers of. 

 *Ficus arenacea Lesquereux. 

 *Ficus impressa. 

 *Ficus cockerelli Knowlton. 

 *Ficus navieularis Cockerell. 

 *Ficus planicostata? Lesquereux. 

 *Ficus praetrinervis Knowlton. 



Ficus sp., new. 



Ficus? sp. 

 *Sequoia longifolia Lesquereux. 



Geonomites cf. G. ungeri Lesquereux. 

 Ilex? sp. , 



*Juglans praerugosa. 

 *Laurus wardiana Knowlton. 



Mimosites? sp. 



Mimosa sp.? < 



*Myrica torreyi Lesquereux. 



Paliurus zizyphoides? 



Palmoxylon sp.', new? 

 *Pecopteris sepulta Newberry cf. Hollick. 

 *Phyllites sp. 



Pistia corrugata? Lesquereux. 



Platanus marginata (Lesquereux) Heer. 

 *Platanus platanoides (Lesquereux) Knowlton. 

 *Rhamnus elegans Newberry, 

 *Rhamnus saliciformis Lesquereux. 

 *Sabal montana Knowlton. 

 *Salix elongata? Al. Braun, 



Salix sp. 

 *Sequoia reiehenbachi (Geinitz) Heer. 



Sequoia sp. 



Woodwardia, new, nearest to W. crenata Knowlton. 

 *Zizyphus minimus Knowlton. 



An analysis of the above list shows that it 

 contains 48 forms, of which 26, marked with 

 an asterisk in the list, are named species having 

 a distribution outside this area. Of these 

 26 species n8 less than 25 are found also in the , 

 Laramie of the Denver Basin, and it therefore 

 seems legitimate to conclude that the age qf 

 the beds is the same in the two areas. As set 

 forth at length on page 60, the section of " Lower 

 Laramie" rocks has a thickness of about 6,000 

 feet. According to Veatch, this thick section 

 is separated from the overlying beds (now 

 called the Ferris formation) by an unconformity 

 which he regarded as profound, because it was 

 believed to have involved the removal of more 

 than 20,000 feet of sediments. This uncon- 

 formity was presumed to be the same as that 

 which separates the Lararnie from the over- 

 lying Arapahoe and Denver formations in the 

 Denver Basin, but as a result of later work 

 Bowen would place this unconformity at the 

 top of the Ferris formation and not at its base, 

 though not denying the possibility of an un- 

 conformitv at the base of the Ferris. That 



