Ill 



THE JUNGERMANNIALES 



119 



Representatives of the Acrogynse are found in all parts of 

 the world, and many of the larger genera are cosmopolitan. 

 It is in the wet mountain forests of tropical and subtropical 

 regions that they reach their greatest development, both as 

 to size and numbers. In these regions they replace to a great 

 extent the Mosses of the more northern forests. Some of 

 them are extremely minute, and grow as epiphytes upon the 

 leaves and twigs of trees and shrubs, or even upon the leaves 

 of ferns, or of larger Liverworts. Some of the larger forms, 

 like species of Bazzania or Schistochila (Fig. 63) are conspicu- 

 ous and characteristic plants. 



Classification of the Acrogynce 



In attempting to subdivide 

 this very large family, numer- 

 ous difficulties are encountered. 

 Their affinity with the Ana- 

 crogynse is unmistakable, but it 

 is highly improbable that the 

 family, as a whole, has had a 

 common origin. It is much 

 more likely that different types 

 of leafy Liverworts have origi- 

 nated quite independently from 

 different anacrogynous proto- 



FiG. es.-schistockiia Ippendicuiata. A. typcs. While thc Acrogyuae 

 plant of the natural size; B, two sliow a good deal of Variation, 



dorsal and one ventral leaf (v), X.. ^^^ differences are UOt COUStaut, 



and the different groups or sub-families merge so into each 

 other as to make a satisfactory division of the family almost 

 hopeless. According to Schiffner ( i ) , the only one of the sub- 

 families which he recognizes, which is clearly delimited, is 

 the Jubuloidese. He recognizes the following sub-families 

 (Schiffner (i), p. 74) : 



I, Epigonianthese; ILTrigonanthese; III, Ptilidioideae ; 

 IV, Scapanioide^e ; V, Stepaninoidese ; VI, Pleurozioideae ; 

 VII, Bellincinioide^; VIII, Jubuloideae. 



