346 PART IV. CLASSIFICATION. 



shaped capsule*, the long setae have the peculiarity of contracting into 

 a spiral on being wetted and dried ; it is common on walls and paths. 

 Pol ijtricJium formosum (Fig. 211) and other species are the largest of our 

 indigenous acrocarpous Mosses ; they have large dark green leaves and 

 long hairy calyptrse an'd are common in woods and on heaths. 



The following are among the more familiar species of pleurocarpous 

 Mosses : 



Fontinalis antipyretica floats in water. Neckera crispa, with flat out- 

 spreading leaves, grows on rocks. Tliuidium ahutimim and other species 

 grow on banks and in woods; they have regular, piniiately-branched stems, 

 and very small, closely-set leaves. Leucodon sciuroides is common on 

 tree-trunks. Bracliytliecium rutabulum is common in woods. Eurhyncliium 

 prcelonyum, with long creeping stems, occurs in woods and damp gardens. 

 Hypnum cupressiforme is very common on tree-trunks, and H. cuspidatum 

 and giganteum in bogs and ditches. Hylocomium triquetrum is very 

 commonly used for garlands; this and H. splendens, with remarkably 

 regular ramification, are both common in woods. 



GROUP III. 



PTEEIDOPHYTA (Vascular Cryptogams). 



The distinguishing characteristics of the plants forming this 

 group are the following : The life-history presents a well-marked 

 alternation of generations, as in the Bryophyta ; but here it is the 

 sporophyte which is the more conspicuous form, constituting " the 

 plant." The sporophyte becomes quite distinct from the gameto- 

 phyte at an early period : it is differentiated (with but few* 

 exceptions) into root, stem, and leaf ; and in all cases it contains 

 well-developed vascular tissue. The gametophyte, generally 

 termed the protliallium, is a relatively small thalloid body, usually 

 short-lived, containing no trace of vascular tissue. 



The group includes the three classes, Filicinse, Equisetinre, 

 Lycopodinse. 



The SPOROPHYTE is developed from the oospore, which undergoes 

 division, in all cases, into an epibasal and a hypobasal half, by a 

 basal wall which is either more or less nearly parallel to the long 

 axis of the archegonium (Leptosporangiate Filiciuse) or more or less 

 nearly transverse to it : the epibasal half usually faces the neck of 

 the archegonium, but in the Lycopodinse the hypobasal half occupies 

 this position. In the Filicinae and Equisetinse, the formation of 

 the basal wall is followed by the formation of another wall at 

 right angles to it (qiiadrant-walT) so that the embryo now consists 



