West. — A Contribution to the Study of the Marattiaceae. 37 9 
large leaf-gap is formed by the departure of the trace of the second leaf 
from the convexity of the crescent-shaped stem-stele ; this leaf-trace consists 
of four strands which pass off at various levels from the margins of the 
foliar gap (Text-fig. 11, v-vii). The stem-meristeles meanwhile branch and 
anastomose, and the commissural strand pursues a roughly spiral course 
through the central ground-tissue, fusing with the stem-meristeles above 
the foliar gaps. In this way, then, the protostele becomes directly 
transformed into a typical dictyostele without the intervention of a sole- 
nostelic stage. The subsequent stages are essentially similar to those 
described by Brebner ( 12 ) for the sporeling of Danaea simplicifolia , Rudge, 
and by the present writer for the young sporophyte of Danaea nodosa, Sm., 
the radial symmetry being retained throughout. 
Vascular Anatomy of the Petiole of the Adidt Sporophyte . The leaf- 
trace, 1 both in Danaea alata and in Danaea nodosa, is made up of an abaxial 
arc of several strands and of adaxial wings derived from the two strong 
lateral strands which generally branch two or three times whilst still within 
the cortex of the stem (PI. XXI, Fig. 1, a). No strands from the inner 
cylinder contribute directly to the leaf-trace, but a varying number of 
internal accessory strands, similar in every respect to those described by 
Gwynne-Vaughan ( 30 ) for K aulfnssia and for Archangiopteris , arise from the 
strands of the abaxial arc near the base of the petiole, travel across the 
ground-tissue, and unite with the terminal strands of the primary ring. 
The presence of these so-called internal strands of the leaf-trace is a very 
characteristic feature of this group of Ferns. Above the region of the 
basal pulvinus the strands of the horseshoe curve anastomose repeatedly; 
sometimes the terminal (i. e. adaxial) strands fuse together to form 
a single large strand with adaxially directed protoxylem groups (Text-fig. 
12 , i-ix). 
The vascular supply of the pinnae is interesting, but since a considerable 
variation in the number and shape of the vascular strands was found 
among the specimens examined, two typical cases are described in some 
detail below. 
Case /. The arrangement of the strands represented in Text-fig. 12, i, 
was found a short distance below the point of insertion of the lowermost 
pinnae. Each leaflet of the lowermost pair receives four strands ; three of 
these (numbered 1,3,5 and 2, 4, 6 respectively) proceed from the flank 
of the horseshoe curve, while the fourth (numbered 7 and 8 respectively) 
arises from the edge of the large strand which is formed by the fusion of 
the terminal (i. e. adaxial) strands of the petiolar curve with the internal 
accessory strands of the basal pulvinus. Occasional branchings and anasto- 
mosings occur in these pinna-traces (Text-fig. 12, ii-vii). Branches arising 
1 For a brief, but comprehensive, summary of previous work on this subject consult Tansley, 
A. G. : Evolution of the Filicinean Vascular System. Reprint from New Phytologist, vols. vi and 
vii, 1907-8. 
