THE ARCHEGONIAT^E 



219 



the small appendage at the base, arises from the epibasal half of the two-celled 

 embryo. 



Classification of the Acrogynae 



The division of the Acrogynse into separate families offers some 

 difficulties, as the group 

 as a whole has com- 

 paratively few marked 

 differences. The follow- 

 ing families have been 

 proposed by Schiffner 

 (Engler and Prantl, 4) : 

 I. Epigoniantheae ; 



II. Trigonantheae ; 



III. Ptilidioideae; 



IV. Scapanioideae ; 

 V. Stephaninoideae; 



VI. Pleurozioideae ; 

 VII. Bellincinioideae ; 

 VIII. Jubuloideae. 



CLASS II. 

 ANTHOCEROTALES 



The Anthocerotales 

 include three genera 

 which agree closely 

 among themselves, but 

 are so different from 

 the other Hepaticse, 

 with which they are 

 usually associated, that 

 it seems best to sepa- 

 rate them as a class 

 coordinate with the 

 whole of the Hepaticae. 



The gametophyte (Fig. 182) is a simple thallus in most species, 

 but in Dendroceros there is sometimes an indication of a rudimentary 

 leaf -formation, not unlike that of Fossombronia. In this genus, the 

 thallus has a definite midrib, while the rest of the thallus is but 

 one cell thick. In the other genera, Anthoceros and Notothylas, 

 the thallus is fleshy and has no midrib. Dendroceros is a tropical 

 genus, and is epiphytic in its habits. The other genera occur also 

 in temperate regions and are terrestrial. 



FIG. 180. Lejeimia metzgeriopsis. A, thallose proto- 

 nema with terminal leafy buds, b (X 14). B, gem- 

 ma of C'ololejeunia Goebelii. (After GOEBEL.) 



