130 



LARAMIE FLORA OF THE DENVER BASIN. 



This species is undoubtedly most closely 

 related to Artocarpus dissecta Knowlton, 79 

 from the Vermejo formation near Walsenburg, 

 Colo., with which it agrees in general type, 

 though differing in a number of important par- 

 ticulars. In the first place, although, of course, 

 this difference is not of cardinal importance, 

 it may be mentioned that Artocarpus dissecta 

 is nearly twice the size of the present species. 

 In A. dissecta the lower lobes are attached by 

 the whole width of the segment, and the main 

 secondary or "midrib" is very close to the 

 lower margin, which gives the segment the 

 appearance of being cut away on the lower 

 side. In A. liriodendroides, on the other hand, 

 the lower segment is attached by a much con- 

 tracted base, and the "midrib" is practically 

 central. In shape and major nervation the 

 upper segments appear to be much the same 

 in both forms. The petiolar wing connecting 

 the segments is much more pronounced in 

 A. liriodendroides and extends down the petiole 

 below the lower segment for a greater distance 

 than in A. dissecta. It is quite possible that 

 if a series of specimens from both localities were 

 available the two forms might be shown to 

 approach more closely or even to combine, 

 but with only a single example from each 

 locality, the forms seem sufficiently distinct 

 to warrant different names. 



The leaf here described has an undoubted 

 resemblance to what has been called Lirioden- 

 dron from . the Dakota sandstone of Kansas, 

 being in a way intermediate between L. 

 pinnatifidum Lesquereux 80 and L. snowii Les- 

 quereux. 81 The former is described by its 

 author as "pinnately, alternately lobed; lobe3 

 short, obtuse truncate or angular, abruptly 

 narrowed into an obtusely lobate or subtruncate 

 apex, separated by broad, unequal sinuses," 

 and the latter is described as "pinnately, hori- 

 zontally divided into linear, obtuse lobes, distant 

 and distinct for their whole length, attached by 

 their whole base to the thick median nerve 

 (petiole) like pinnules of a compound leaf." 

 The specimens upon which L. pinnatifidum is 

 based are imperfect, so that it is not possible 

 to make out the whole leaf with satisfaction, 

 but it appears to have had at least three pairs 



ra Knowlton, F. H., U. S. Geol. Survey Prof. Paper 101, p. 267, pi. 42, 

 fig. 6, 1918. 



»o Lesquereux, Leo, The flora of the Dakota group: V. S. Geol. Surfey 

 Mon. 17, pi. 27, figs. 4, 5, 1892. 



8i Idem, pi. 29, figs. 1, 2. 



of large, obtuse, irregularly, quadrangular, 

 alternate lobes, which are separated by broad, 

 rounded sinuses. The portion of the blade 

 between the lobes is sufficiently broad to sup- 

 port a considerable nervation, whereas in the 

 Laramie species the interlobular margin or 

 wing is too narrow to be provided with nerva- 

 tion. Superficially the leaf of Artocarpus 

 liriodendroides appears to be most like L. snowii, 

 for unless examination is careful enough to 

 disclose the narrow wing between the lobes 

 it seems essentially identical with that species. 

 Occurrence: Laramie formation, Coal Creek, 

 Boulder County, Colo., collected by N. L. 

 Britton about 1884. 



Ficus? smithsoniana? (Lesquereux) Lesquereux. 



Plate XXI, figure 4. 

 Ficus smithsoniana (Lesquereux) Lesquereux, Tertiary 

 flora: U. S. Geol. Survey Terr. Kept., vol. 7, 

 p. 200, pi. 32, fig. 5, 1878. 

 Knowlton, TJ. S. Geol. Survey Prof. Paper 101, p. 

 305, 1918. 

 Juglans smithsoniana Lesquereux, TJ. S. Geol. and Geog. 

 Survey Terr. Ann. Rept. for 1872, Supplement', 

 p. 16, 1873. 



The type of this species is preserved in the 

 collections of the United States National 

 Museum (No. 106a) and is said to have come 

 from "Fishers Peak, Raton Mountains, N. 

 Mex." It is preserved on the same piece of 

 matrix as the type of Geonomites ungeri 

 Lesquereux, and there is thus every reason to 

 suppose that the locality is correctly stated. 

 However, no additional specimens of this 

 species were found in the very ' extensive col- 

 lections from the Raton Mesa region recently 

 studied. 



In the collections from Mount Carbon, 

 Morrison, Colo., there is a single example that 

 may be this species. The matrix on which it 

 is preserved is the coarse-grained sandstone 

 so characteristic of many of the Laramie 

 deposits and hence is not well fitted to retain 

 the details of nervation. The primary nerva- 

 tion is similar to that of the type, but the shape 

 of the blade differs somewhat in being a little 

 broader and more tapering both at base and 

 apex. At least this identification must be 

 considered as open to some question. 



Occurrence:' Raton formation (type), Fishers 

 Peak, Raton Mountains, Colo. Laramie for- 

 mation, Mount Carbon, Morrison, Colo., col- 

 lected by Arthur Lakes, 1890. 



