300 WHITE—OMPHALOPHLOIOS, A NEW LEPIDODENDROID TYPE. 
cortical impression, the important specimens will be described somewhat 
in detail, in order to present for future consideration all the evidence at 
hand as to the organs or appendages of the tree, and its systematic posi- 
tion. It is unfortunate that in this, as well as in most other peculiarly 
American types of Carboniferous plants, no material is at hand to show 
the internal organization of the tree, which is represented only by some- 
what flattened casts of trunks and branches, or by cortical impressions 
revealing only superficial details. 
DeTAILED DerscrIPpTiON OF ORIGINALS OF LEPIDODENDRON CYCLOSTIGMA 
The bolsters of these compressed trunks are, as was stated by Lesque- 
reux, variable in form as well as size. Illustrations of these varying 
forms, which sometimes suggest the Lepidodendron clypeatum of Lesque- 
reux,* are seen in plate 20 and plate 21, figure 4, and plate 22, figures 2 
and 5. The fragmental impression, a portion of which is seen in the - 
first plate, is 81 centimeters in length and 13 centimeters in width, the 
entire breadth of the trunk being unknown. It is probable. however, 
that some of the trunks of this species grew to a considerable diameter, 
The figured fragment shows the impression or mold, over most of which 
the outer very thin cortex or epidermis still adheres. Nevertheless, that 
phase in which the bolsters are represented at their longest and in their 
more distinctly Lepidodendroid aspect is well seen, the fine separative lines 
of the rhomboidal, acute bolsters being clear. while the general features 
of the subtriangular or somewhat circular central convex areas, which, 
as we shall see, represent large compressed, roundish bosses, are in agree- 
ment with the original figured by Lesquereux.f It will be observed 
that the bolsters are low, rounded, and destitute of keel or caudal orna- 
mentation either above or below the scar; that the central convex area, 
as compressed, varies from round to more or less distinctly triangular, and 
that the boundary of the latter is often a sharp, clear furrow, from the 
lateral angles of which short, quickly vanishing lines pass outward to 
ward the curved bolster margin, which they fail to reach. Other com- 
pressed specimens, mostly impressions, to which reference will be made, 
show the great variability in the aspect of these central areas. The pho- 
tograph of the example under consideration fails to show a punctiform 
mammilla situated near the center of the convex area or but avery little 
nearer the lower border. This, which we may temporarily designate as 
the central trace, is visible to the unaided eye, as are also, in a few in- 
stances, two rather indefinite, rounded, low, vertical grooves crossing 
*Geol. Penna., ii, 2, p. 875, pl. xv, fig. 5; pl. xvi, fig. 7. Coal Flora, ii, p. 380, pl. Ixiv, fig. 16. 
+ Coal Flora, Atlas, pl. lxii, fig. 5; no. 5501 of the Lacoe collection, U. 8. N. M. 
