I 



The Genus Riccardia in Chile. 147 



obliquely and some of them, although narrower than the main axis, 

 show a blunt apex and long-continued growth. Since these 

 branches tend to increase in width it is probable that they would 

 develop into new thalli under suitable conditions. Branches with 

 long-continued growth are mostly 0.4-0.6 mm. wide and may reach 

 a length of i cm. or more. Other branches are narrower and 

 shorter, their growth being soon brought to an end. All the 

 primary vegetative branches give off numerous secondary branches 

 and these in turn usually give oft tertiary branches, so that the 

 apical portion of the thallus represents a broad and complicated 

 photosynthetic branch-system. The flattened ultimate branches, 

 whether secondary or tertiary, are mostly 0.4-1 mm. long and 

 0.2-0.3 mm. wide. In some cases tertiary branches or the apical 

 portions of secondary branches become subterete with rounded 

 sides and may be interpreted as stolons. The flattened ultimate 

 branches (Fig. 4, G) are mostly ten to twelve cells broad and four 

 cells thick in the middle ; they are similar in structure to the main 

 axis and the marginal row of enlarged cells is sometimes fairly 

 distinct. The stolons (Fig. 4, H) are mostly eight or nine cells 

 broad and six or seven cells thick, and the surface-cells along the 

 edges are scarcely larger than the others. 



Stephani's description and figure give a good idea of R. chilensis, 

 and he lays especial emphasis on the marginal row of cells. 

 According to his account the type material was sterile. The writer 

 has been fortunate enough, however, to separate out a few female 

 plants and is thus able to give some idea of the female branches. 

 These, in most cases, arise directly from the main axis and are 

 exceedingly short. In a single instance a branch had proliferated 

 and grown out into a subdivided strap-shaped extension. The 

 upper surface of the branch is directed forward rather than 

 upward, and very few archegonia are developed. The wings, 

 which are apparently the only involucral structures formed, are 

 mostly two to four cells broad and vaguely crenulafe or denticulate 

 from projecting cells. The very young "calyptra" shows a small 

 corona and a surface roughened by cells which are splitting off. 

 A single fragment with four short and simple male branches has 

 likewise been distinguished, but the inflorescences are poorly pre- 

 served and show no features clearly except the spreading wings 

 one cell broad. 



