502 Bowei\—Studies in the Phytogeny of the Filicales. 
which are long and narrow, with a dark brown central rib. The distal end 
thins out to an acuminate apex, and may be terminated by a glandular 
cell. The midrib may be more than one layer of cells in thickness, and is 
composed of oblong cells with thickened brown walls, similar in their 
character to those forming the whole upper part of the hair in Dipteris . 
Laterally the appendage is flattened out into flaps of thin-walled cells, 
a single layer in thickness, while at the margins are borne fringes of hairs, 
each terminated by a glandular cell. At the base of the scale there remains 
for a time an active formative zone of delicate meristematic cells, a condi¬ 
tion which compares with what is seen in Matonia , Dipteris , and Cheiro- 
pleuria. The whole scale is thus much more elaborate than in any of the 
preceding Ferns. But it may be held as a possible derivative of the type 
seen in Dipteris. A widening of the margins into thin lateral flaps, an 
elongation of the bluntly projecting marginal cells of Dipteris into multi¬ 
cellular hairs, and the appearance of terminal glandular cells upon them 
would convert the type of hair seen in Dipteids into the scale of the rhizome 
of Platycerium . And both are possible derivatives of the simple hair of 
Matonia , or of Cheiropleuria. 
Anatomy. 
I am not aware of any detailed account having yet been given of the 
internal structure of Cheiropleuria. Christ (Farnkrauter, p. 128) makes 
a statement in his generic description which suggests a solenostelic 
structure; but none of my specimens confirms this. Sections of the 
rhizome, at whatever level or age of the specimen, show a protostelic 
structure. The stele is of considerable size, and in structure and in form 
it resembles closely that of the protostelic Gleichenias, such as G. flabellata, 
or dichotoma (PL XXIV, Figs. 8-12). It will then be unnecessary to describe 
it in detail. But it is to be noted that the protoxylem which enters from 
the leaf as a double strand (Fig. 11) merges at once on entry into a single 
strand (Figs. 10, 12), and can be traced only for a very short distance 
downwards below the point of entry. Accordingly, as a rule, only one 
such strand can be recognized in a given transverse section of the protostele. 
The xylem consists of rather wide tracheides, interspersed with parenchyma, 
which is more plentiful towards the centre of the stele. The band of phloem 
is characterized by narrow sieve-tubes, while the rather prominent proto¬ 
phloem is composed of specially small elements, the walls of which appear 
brown under safranin-haematoxylin. Outside this are about three layers 
of pericycle, and finally the endodermis. This delimits the stele from the 
broad peripheral cortex, of which the outermost layers are brown and 
sclerosed. 
The leaf-traces are seen to originate from this protostele alternately 
right and left of the median line, on the upper side of the creeping or 
