336 WHITE—OMPHALOPHLOIOS, A NEW LEPIDODENDROID TYPE. 
obcordatus by Professor Lesquereux.* It is possible that both are refer- 
able to the same species. The oval bosses as well as the central mammille 
are very clear in this specimen. 
Another fragment, a part of which is photographed in plate 21, figure 
2, shows but a faint and fragmentary trace of the bolsters here and there. 
The surface is nearly flat, the larger bosses being nearly obliterated, only 
the leaf angle and the oval bosses being left in slight relief. Both the 
inner and the outer borders of the oval boss are defined, as is imperfectly 
seen in the photograph. This stem, the epidermis of which is in part 
preserved, is further ornamented by several large, shallow pits of two 
sorts. The larger ones in the lower portion of the specimen are nearly 
circular, and nearly equal in size the larger bosses of the other speci- 
mens. The details of their interiors are obscure. They show, however, 
traces of the two low, rounded, vertical ridges passing across them, with 
a central oval trace. These shallow, rounded pits, which are possibly 
caused by collapse of the large bosses, may conform with the convex - 
- areas in the bolsters in the types studied by Lesquereux, the vertical 
furrows and trace agreeing perhaps with the ridges and trace in 5502 of 
the Lacoe collection. The other form of depression seen in figure 2 is 
often elliptical, traversing vertically the obscurely indicated and wrinkled 
outline of the large boss. These elliptical pits are evidently coincident 
with the area and position of the vertical, rounded furrows seen in the 
round pits on the same fragments. The leaf angle and oval boss are 
wholly obscured. This elliptical or horseshoe appearance of the vertical 
ridges crossing the larger bosses, while never conspicuous in any of the 
specimens, is present and faintly visible in many of the bolsters of the 
fragment (figure 4 on plate 21). Although but little wider than the oval 
boss it is much longer, extending in this case a little beyond the large 
boss and including, as usual, the upper punctiform trace near the trun- 
cated upper margin of the bolster. In some respects the large, shallow 
depressions in this specimen are perhaps analogous to the abnormal or 
strobiliferous scars seen in some of the Sigillariz. 
DIAGNOSIS OF OMPHALOPHLOIOS CYCLOSTIGMA 
A résumé of the superficial characters preserved in the compressed 
cortex in this unique species is given in the following diagnosis : 
Omphalophloios cyclostigma (Lx.). 
Stems or trunks of considerable size, the larger covered by more or less clearly 
defined Lepidodendroid bolsters. Bolsters contiguous, sometimes partially obscure, 
* Rept. Geol. Survey Illinois, ii, 1866, p. 457, pl. xli, fig. 1 (not figs. 2, 2a). 
