568 FILICALES 
were indusiate, as in Mavtonza itself. The difference does not seem to 
be an essential one, and in face of the correspondence of the Ferns in 
question in other respects it 
cannot be -held to invalidate 
Hh 
=a SZ the reference of these, and of 
certain other Mesozoic Ferns 
to the family of the Maton- 
ineae. 
re 
AM 
Z 
iN 
A 
ANATOMY. 
Fic. 318. The mature rhizome of 
Az=pinnule of Laccopteris Woodwardi from the inferior 7 = 
oolite of Yorkshire: the hemispherical bosses show the Matonia shows the most com 
position of the sori (No. 217, Brit. Mus.). S=pinnule of ica’ i tructur 
Laccopteris polypodtioides with sori and soral impressions. plic ted solenostelic structure 
Upper shale, Gristhorpe Bay (No. 2522, Brit. Mus.). C= known in Ferns: in the young 
pinnule fragment from the inferior oolite of Stamford (No. 7 : 
52867, Brit. Mus.). (After Seward, from drawings by Miss stem, however, simpler condi- 
G. M. Woodward.) “ rf 
tions are found which suggest 
how the final condition was probably arrived at. In the most complex 
rhizomes three concentric vascular rings may be found embedded in 
parenchyma, and each showing the typical solenostelic structure. Each is 
limited externally and internally by an endodermis and pericycle, while 
between these in each is a continuous ring of xylem, with phloem on either 
side of it. The arrangement of this solenostelic structure is represented 
diagrammatically in Fig. 319, together with its connections with the leaf- 
trace. The latter is in these Ferns one continuous band, with involuted 
margins, which are shown in Fig. 319 c: this drawing also indicates that 
foliar gaps occur, and shows how the leaf-trace is directly continuous with 
the outer and middle of the concentric rings at the node. There may also 
be a connection with the inner ring; but this occurs at some little distance 
from the actual node, and so is not shown in the drawing. The result 
is that the whole system is connected, but only at intervals of its whole 
length, while there is also connection through the leaf-gaps between the 
parenchymatous tracts in which the cylinders are embedded. 
The ontogeny gives the suggestion how this complicated structure is 
.to be placed in relation to that of other Ferns. The young axis contains 
at first a slender protostele; but this simple stele soon expands, and a 
strand of phloem appears in the midst of the xylem. This internal phloem 
appears to be a phloem-pocket decurrent from the adaxial surface of the 
second leaf, but there is as yet no true leaf-gap. The stele soon widens. 
into a solenostele with internal endodermis and central parenchyma. 
Meanwhile at the nodes a ridge of xylem projects internally, which becomes 
more prominent at subsequent nodes, and is continued forwards into the 
internode further and further at successive nodes, till that of one node 
eventually connects with a similar xylem-dilatation of the next node 
(Fig. 319 A). A continuous central strand is thus produced, which is 
connected at the nodes with the outer cylinder. 
