INTERPRETATION OF THE PARTS. 333) 
which now seems either close within or partly between the vanishing 
ends of the lower curves of the oval, might be correlated with the trace 
just above the foliar cicatrices in Sigillaria and Bothrodendion. On the 
other hand, in opposition to the above hypothesis, the interior details of 
the oval, the basal angular or deltoid scar, and the superior trace in the 
bolster, as well as the form of the bolster itself, seem to be arraigned. 
The oval boss comprises an outer zone about .5 millimeter in width in- 
closing an oval depression. I have found no traces within the latter 
except the umbilicate trace, generally near the upper end, and this shows 
on the cortex asa minute pit bordered by a raised carbonaceous rim. 
In the impressions this trace causes a minute projecting point. Next, 
the slightly raised transverse cicatrix at the base of the oval boss and on 
the lower edge of the large boss, showing a surface of separation, appears 
to be supplied with a vascular trace and occupies the position of a leaf 
in the Lepidodendroid bolster. There are in a few instances even slight, 
though quite uncertain and perhaps worthless, signs of the subfoliar ap- 
pendages. Much depends on the relation of the oval boss to the trans- 
verse scars, which I have designated as leaf cicatrices, and these relations 
can perhaps be ascertained only by the discovery of additional material. 
On those bolsters the cortical tissue of which appears best preserved and 
intact the rim of the oval boss would seem in some cases, as shown in 
the photograph, plate 23, to be nearly, but not. quite, tangential to the 
transverse scar, the punctiform trace being shehtly within the outer oval 
boundary. In this matter the evidence of other bolsters would, how- 
ever, seem somewhat conflicting. It should be remarked that in those 
bolsters in which the base of the oval is most clearly defined the vertical 
diameter of the transverse or leaf scar seems considerably foreshortened 
in the course of fossilization. 
Ifit be found, as seems to be indicated in some instances, especially 
where the protruding leaf scar is abraded, that the rim of the oval boss 
is really in union by a narrow connection with what is here, perhaps 
erroneously, interpreted as the leaf scar, the conditions will be perhaps 
best satisfied by assuming that the oval boss was the seat of some ex- 
pansion or unfamiliar structure on the ventral surface at the base of the 
leaf of which it would form a part. In such an arrangement the trace 
above the large boss might be the homologue of the so-called “ligule,” 
or the “sporophyll” scar, while the small umbilicate trace in the central 
depression would constitute a new basis for speculative analogy. How- 
ever, while far from conclusive, the signs at hand do not appear to favor 
that hypothesis. 
Assuming that I am not mistaken in treating the transverse basal scar 
as proper to the leaf rather than as a mere fracture or abrasion, we would 
