342 PART III. THE CLASSIFICATION OF PLANTS. 



The genera are : Kiccia, of which there are many species arranged in the 

 two sections Euriccia and Eicciella ; Eicciocarpus, represented only by th 

 species R. natans ; Oxymitra (Tesselina). 



Fam. 2. Corsiniece. The gametophyte resembles, 

 on the whole, that of the lower Marchantiese in it< 

 general structure ; it has a midrib which projects 

 on the under surface ; it is characterised by the 

 arrangement of the archegonia, which are borne in 

 dorsal groups, not on a receptacle (indicated in 

 Corsinia), but in pits, the surface of which produces 

 a dense growth of hairs. The spoiophyte is differ- 

 entiated into foot and capsule ; the wall of the 

 FIG. 242. Dorsal surface 



of portion of thallus of capsule persists until the spores are ripe ; some of 

 Eiccia glauca (nat. size): the archesporial cells are sterile and, in Boschia, 

 v the dorsal furrows of the become elaters. 



lobes 5/sporoRonia develop- The f am ii y includes the two genera Corsinia and 



Boschia (Funicularia): each genus has but a single 



species ; Corsinia marchantioides is European ; B. Weddellii is found in Brazil. 

 Fam. 3. Marchantiece . The gametophyte has a well-developed air-chamber 

 layer on the dorsal surface ; the air-chambers have each a well-marked pore, 

 which is either simple or compound ; in the higher forms the air-chambers are 

 filled with filaments of assimilating cells : on the ventral surface are two rows 

 of scales and two kinds of root-hairs. The arcbegonia are borne in groups on 

 a receptacle which is either dorsal, as in the lower forms, or terminal on a 

 gametophore, as in the higher. The sporophyte is differentiated into foot, seta, 

 and capsule ; some of the archesporial cells are sterile, and become elaters. 

 The following sections of Marchantieee may be distinguished : 



a. Astroporce : characterised by the thickening of the radial walls of the cells 

 surrounding the simple pores of the air-chambers, in which there is no develop- 

 ment of filamentous assimilatory tissue. There is no antheridial receptacle in 

 Sauteria and Clevea, where the antheridia are borne in a row on the surface of 

 a ventral antheridiophore, but it is well-developed and dorsal in Peltolepis ; 

 there is a terminal archegoniophore in Sauteria, with usually a single ventral 

 furrow, and in Peltolepis, with two ventral furrows ; but in Clevea there is no 

 archegoniophore, but a dorsal stalked unfurrowed receptacle. 



Genera : Sauteria, Peltolepis, Clevea. 



b. Operculatce : characterised by the mode of dehiscence of tLe capsule, the 

 upper third of the wall being thrown off as an operculum : the family includes 

 the genera Plagiochasma (Aytonia), Eeboulia, Duvalia (Neesiella), CJrimaldia, 

 Fimbriaria (Hypenantron). The pores are simple, and the air-chambers usually 

 do not contain filamentous assimilatory tissue. The archegonial receptacle is 

 dorsal and stalked in Plagiochasma and Grimaldia ; in the other genera it is 

 borne on an archegoniophore with a single ventral furrow. The antheridial 

 receptacles are sessile ; in Duvalia they are terminal. 



c. Targionice, including Targionia and Cyathodium. The archegouia are 

 developed in a sessile group at the apex of a branch ; if one of the archegonia 

 is fertilised, the further growth of the branch is arrested, but if not, growth is 

 resumed, and the group of archegonia becomes dorsal ; the antheridia aie borne 



