110 



LARAMIE FLORA OF THE DENVER BASIN. 



to be very well characterized, being bipinnate, 

 or perhaps it would be better to say bipinnati- 

 fied, with the pinnae alternate, at a low angle 

 of divergence with the main rachis, and lanceo- 

 late in general outline. They are cut nearly 

 to the secondary rachis, with numerous linear- 

 lanceolate, rather obtuse segments. In the 

 type species figured in the "Tertiary flora" 

 (pi. 4, fig. 13) the segments of the pinnae are 

 short, being from 7 to 9 millimeters in length, 

 and have from five to seven pairs of simple 

 nerves. 



The type of Aspidium goldianufn Lesquereux 

 (now Dryopteris lesguereuxii) is said to have 

 come from Golden, Colo., and an examination 

 of the specimen (No. 26, U. S. Nat. Mus.) 

 appears to confirm this statement; in any event 

 there is no tangible evidence to the contrary. 

 The species has not been noted in any of the 

 recent collections from Golden. 



Occurrence: Laramie formation, Golden, 

 Colo. 



Dryopteris? carbonensis Knowlton, n. sp. 



Plate XX, figures 3-5. 



Dryopteris? carbonensis Knowlton [nomen nudum], U. S" 

 Geol. Survey Bull. 696, p. 249, 1919. 



Fronds once pinnate ( ?) ; pinnae probably 

 lanceolate, deeply pinnatified, the divisions 

 nearly opposite, narrowly deltoid or broadly 

 lanceolate in outline, with obtusely acuminate 

 apex and perfectly entire margins; secondary 

 rachis strong; midnerve of segments thin, 

 practically straight; nerves obscure, apparently 

 remote and simple; fruit unknown. 



This species is based on the three fragments 

 figured and is apparently quite distinct from 

 anything from the true Laramie heretofore 

 described. Whether it belongs to the genus 

 Dryopteris is not by any means certain, for 

 without fruit that point can not be 'positively 

 ascertained, but from its general resemblance 

 to certain species of this genus I have decided 

 so to refer it. It is, for example, quite like 

 some of the larger pinnae of Dryopteris gol- 

 diana (Hooker), a living species of eastern 

 North America. 



From its general resemblance to the above- 

 mentioned living species, I have assumed that 

 it had once-pinnate fronds with numerous 

 lanceolate pinnae, but this, of course, is largely 

 conjecture. The divisions of the pinnae are 

 cut a little more than half the distance to the 



midvein. They are slightly scythe-shaped 

 and have rather acute apices. The secondary 

 nerves of the divisions appear to be simple, 

 but the specimens are preserved on a rather 

 coarse grained matrix which is not well suited 

 to preserve the finer nervation, and it is im- 

 possible to say whether they were forked or 

 not. No trace of the fructification is pre- 

 served. 



A single fragment of this species is found also 

 in the collections from Marshall, Colo.; it is 

 without nervation and is on the same piece of 

 rock with Ficus arenacea. 



Occurrence : Laramie formation, Mount Car- 

 bon, Morrison, Colo. ; sandstone near coal seam, 

 Marshall, Colo. ; collected by A. Lakes, 1890. 



Genus PHANEROPHLEBITES Knowlton, n. gen. 



Of the general type of the living Phanero- 

 phlebia, but with thick, fleshy midrib, and few 

 free veins. 



Phanerophlebites pealei Knowlton, n. sp. 



Plate III, figure 5. 



Phanerophlebites pealei Knowlton [nomea nudum], U. S. 

 Geol. Survey Bull. 696, p. 439, 1919. 



Outline of whole frond not known but pre- 

 sumably pinnate, pinnae large, strap-shaped, 

 with apparently entire margins; midrib ex- 

 tremely thick and fleshy; nerves numerous, 

 rather fine, usually forking near the midrib 

 and once or twice before reaching the margin, 

 sometimes free but usually anastomosing ; fruit 

 not preserved. 



This form is represented only by the example 

 here figured, and this is more or less frag- 

 mentary, neither base nor apex being retained. 

 It is now about 12 centimeters long but was 

 obviously Very much longer when perfect. 

 The width was 4.5 or 5 centimeters. The 

 small portion of the margin preserved Shows it 

 to be entire or perhaps slightly undulate. 

 This pinna was evidently of thick substance, 

 as indicated by the very strong midrib and the 

 immersed appearance of the veins. The veins 

 are fine and very close and are more or less 

 conspicuously anastomosed. All the veins 

 fork, and some of them appear to be free, but 

 this feature, owing to the small amount of ma- 

 terial, is difficult to make out. 



It is with some hesitation that this fragmen- 

 tary specimen is described as establishing a 

 new genus. It is aspidioid in general appear- 



