354 



MUSCINE^. 



2. The I'iimily MonocleflB appears, according to the 'Synopsis Hepaticarum,' to 

 contain transitional forms between the Anthoceroteae and the Jungermannieae. The 

 long sporogonium has a longitudinal dehiscence and no columella; and the sexual 

 generation is either thalloid or foliose. 



3. The RicciesB form a flat dichotomously branched thalloid stem, floating in 

 water or rooting in the ground, the apical cells of which, lying close to one another 



Fig. i-^.—Anthoceros Itrvis ; sg the young sporogonium, the letters point to the foot ; L the invohicre ; 

 c—c the columella ^after Hofmeister, X 130) . 



in the anterior depressions of the branches, are stated by Kny to become multiplied by 

 vertical longitudinal partitions, and segmented by walls inclined upwards and down- 



FlG. "iy^.—Riccia glauca; A vertical longitudinal section through the apical region; j apex, b leaves, a young an- 

 theridium, a' older antheridium already surrounded by involucral tissue w ; B rudiment of an antheridium a already 

 overarched ; C young antheridium a in longitudinal section (after Hofmeister, x 500). 



wards. On the upper side a distinct epidermis is differentiated, but without stomata, 

 and beneath this lies the green tissue often provided with air-cavities, which is derived 

 from the upper segments of the apical cells ; the under side is provided with a single 

 longitudinal row of transverse lamellae, which, resulting immediately from the lower 

 segments of the apical cells, must be considered as leaves. Afterwards they split length- 



