THE GREAT GROCPS OF BKYOPIIYTES 



315 



organized into a central stem-like axis bearing two rows of 

 small, often crowded leaves. In consequence of this such 

 Ju ngermannia forms 

 are usually called " leafy 

 liverworts," to distin- 

 guish them from the 

 other Liverworts, which 

 are " thallose." They are 

 also often called "scale 

 mosses," on account of 

 their moss-like appear- 

 ance and their small 

 scale-like leaves. 



205. Anthoceros forms. 

 — This line contains com- 

 paratively few forms, but 

 they are of great interest, 

 as they are supposed to 

 represent forms which 

 have given rise to the 

 Mosses, and possibly to 

 the Pteridophytes also. 

 The thallus is very sim- 

 ple, being differentiated 

 neither in structure nor 

 form, as in the two other 

 lines ; but the special de- 

 velopment has been in 

 connection with the spo- 

 rogonium (Figs. 282, 289). This complex sporogonium 

 (sporophyte) has a large bulbous foot imbedded in the 

 simple thallus, while above there arises a long pod-like 

 capsule. 



The chief direction of the development of tlie three liv- 

 erwort lines may be summed up briefly as follows : The 

 Marcliantia line has differentiated the structure of the 



Fig. 289, 



Anthoceros gracUis : A, several 

 gametophytes, on which sporogonia have 

 developed ; B, an enhxrged sporogonium, 

 showing its elongated character and de- 

 hiscence by two valves leaving exposed 

 the slender columella on the surface of 

 which are the spores ; C, D, E, F, ela- 

 ters of various forms ; G, spores.— After 



SCHIFFNER. 



