KIDSTON : THE FLORA OF THE CARBONIFEROUS PERIOD. 353 
The fructification is in the form of caducous cones (Sigillarios- 
trobus), in some stalked (Plate LY., fig. 4) and placed in the hollows 
between the ribs (Sigillaria mamillaris Brongt., Plate LXI., fig. 3), 
or between the leaves {Sigillaria Brardii Brongt., Plate LYIIL, 
fig. 3 at a) in the non-ribbed species. On falling from the stem the 
stalk leaves a distinct circular, or irregular, shaped scar. The cones 
form regular verticils of a single row {Sigillaria elegans Sternb. sp., 
Plate LYIIL, fig. 3), or of several rows {Sigillaria tessellata var. 
nodosa Bowman sp., Plate LYIIL, fig. 1), or may be somewhat irregu- 
larly placed, especially on the non-ribbed species. In others the 
cones are sessile and form two opposite alternate rows (Plate LI I., 
fig. 4), leaving, when shed, two vertical rows of cup-like depressions 
with a central umbilicus {Sigillaria discophora Konig. sp., Plate LX., 
fig. 1). {Ulodendron L. and H. in part.) 
The Rhizome of most species of Sigillarioe is Stigmaria 
Brongt., in others Stigmariopsis Grand 'Eury. 
The Sigillarioe have been divided into four sections, according 
to whether the stem is ribbed or smooth, and whether the leaves are 
close or more or less distant. These four groups, though well 
characterised in some species, pass into each other, and though they 
may assist in classifying a very difficult genus, they cannot be regarded 
as natural divisions or genera as originally supposed. In all, the 
leaf-scar is of similar structure. 
Section I. — Rhytidolepis Sternberg. 
In this section the stems are distinctly ribbed, the ribs straight 
or slightly flexuous, with surface smooth or variously ornamented. 
Leaf-scars alternate on neighbouring ribs and occupying the whole 
or only part of the width of the rib, either close or more or less distant. 
There is frequently a transverse lunate depression above the leaf-scar. 
The cone scars are situated in the furrows. Typical form, Sigillaria 
mamillaris Brongt. (Plate LXL, fig. 3). 
Section 11. — Favularia Sternberg. 
Stem ribbed, ribs flexuous and divided into sub-hexagonal 
compartments by transverse depressions. Leaf-scars alternate, 
occupying the whole width of the rib and resting on each other, or 
