390 
VASCULAR CRYPTOGAMS. 
upon which too much importance is laid, and therefoi-e run counter to natural affinities 
and cause forms which are widely different to be placed side by side. 
The following new classification lays no claim to be regarded as definitely indicating 
for all time the relationships existing among Vascular Cryptogams, but I believe that 
it corresponds more closely than any previous arrangement with the present state of 
our knowledge on the one hand, and with those affinities which may be said to be 
self-evident on the other. It appears certain that the three Classes here formed, 
the Equisetineae, the Filicinese, and the Dichotomeae, represent three distinct and 
separate types. Great difficulties are offered to the systematic sub-division of the 
Filicinese, for certain groups of them, especially the Osmundaceae, the Schizaeaceae and 
the Gleicheniaceae, have not yet been thoroughly investigated from a morphological 
point of view. 
Sysiemaiic review of the Vascular Cryptogams. 
CLASS VII. 
Equisetine^. 
The spores are of one kind and give rise to prothallia which vegetate independently, 
and which are usually dioecious, the female prothallia being the larger, the male the smaller. 
The second generation consists of a copiously branched stem, with well-defined inter- 
nodes, and bearing relatively small sheathing whorls of Teaves. The branches arise in 
whorls and in strict acropetal order from the nodes of the stem. A root may arise 
below each branch ; its ramification is monopodial. The sporangia are borne upon 
metamorphosed peltate leaves which form a terminal spike : they originate as multi- 
cellular protuberances (emergences), from five to ten in number upon each scale. The 
mother-cells of the spores, it appears, are derived from a unicellular archesporium. 
Both stem and root increase in length by means of a large apical cell which gives rise 
to three rows of segments. The fibro-vascular bundles of the stem are arranged in 
a circle ; their xylem is rudimentary, resembling that of the bundles of Monocotyledons. 
The axial fibro-vascular cylinder of the root has no pericambium. 
Family. (i) Equisetaceae. 
CLASS VIIL 
FlLICINE^. 
The majority of these plants possess spores of one kind only, from which inde- 
pendent monoecious prothallia are developed : but the Rhizocarpese have macrospores 
and microspores forming rudimentary prothallia which never become free from the 
spore. The second generation is a stem bearing numerous well-developed leaves which 
are usually much branched. The stem either does not branch, or it does so but rarely, 
and it bears numerous roots. The sporangia are borne on ordinary leaves, or on leaves 
which have been specially modified: they are usually aggregated into small groups (Sori). 
The sporangia of the Ophioglosseae and Marattiaceae are from the first multicellular, and 
those of the Filices are developed from single superficial cells : the archesporium is 
unicellular. An apical cell is present in the stem and in the root : it forms, in the 
stem, two or three rows of segments, in the root usually three rows. The fibro-vascular 
bundles are generally very well developed, and the central xylem, which consists for 
the most part of scalariform tracheides, is usually surrounded by the phloem. 
Order I. StipulatSB. The spores, so far as is at present known, are of one kind 
and give rise to independent monoecious prothallia. The second generation is a simple, 
