390 



VASCULAR CRYPTOGAMS. 



upon which too much importance is laid, and therefore 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 Equisetinese, the Filicineae, and the Dichotomeae, represent three distinct and 

 separate types. Great difficulties are ofl'ered to the systematic sub-division of the 

 Filicineae, 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. 



Systematic revieiv 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 leaves. 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) Equisetacese. 



CLASS VIIL 



FlLICINE^. 



The majority of these plants possess spores of one kind only, from which inde- 

 pendent monoecious prothallia are developed : but the Rhizocarpeae 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 \. 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, 



