498 CRYPTOGAMOUS OR FLOWERLESS PLANTS. 



beneath, with the fructification immersed in the frond, the sporan- 

 gium bursting irregularly. No involucre nor elaters. Ex. Riccia. 



1169 1170 1171 



940. Sllbord, AnthocerOteee, Terrestrial frondose annuals, with 

 the fruit protruded from the upper surface of the frond. Perianth 

 none. Capsule pod-like, one- to two-valved, with a free central 

 columella. Elaters none or imperfect. 



941. Subord, Marehantiaceae (true Liverworts). Frondose and 

 terrestrial perennials, growing in wet places, with the fertile recep- 

 tacle raised on a peduncle, capitate or radiate, bearing pendent ca- 

 lyptrate capsules from the under side, which open variously, not 

 four-valved. Elaters with two spiral fibres. 



942. Subord, Jungermanniaceae, Frondose or mostly foliaceous 

 plants ; with the sporangium dehiscent into four valves, and the 

 spores mixed with elaters (Fig. 84-86). 



CLASS V. THALLOPHYTES. 



Vegetables composed of parenchyma alone, of congeries of cells, 

 or even of separate cells, often vaguely combined in a thallus, 

 never exhibiting a marked distinction into root, stem, and foliage, 

 or into axis and leaves (94-104, 106). Fructification of the 

 most simple kinds. (Spores often termed sporules, or sporidia.) 



943. Ord, Lichenes (Lichens) form the highest grade of this lower 

 series. They consist of flat expansions, which are rather crusta- 



F1G. 1169, 1170. Riccia natans, about the natural size. 1171. Magnified section through 

 the thickness of the frond, showing the immersed sporangia ; one of which has burst through 

 and left an effete cavity. 1172. Magnified vertical section of one of the sporangia, with the 

 contained spores. 1173. Sporangium torn away from the base, and a quaternary group of 

 spores, united and separated. 



