The Genus Riccardia in Chile. 



157 



In size and method of branching R. conimitra resembles such 

 species as R. fiiscohrunnea and R. alcicornis, but the branches are 

 perhaps a little more differentiated and the histological features 

 afford good distinctive characters. Other important differences 

 are derived from the sexual branches. The species is variable but 

 the range of variability is still incompletely known, owing to the 

 small amount of material available for study. The plants grow 



Figure 6. Riccardia conimitra (Steph.) Evans 



A. Part of male thallus with numerous male branches, x 8. B. Trans- 

 verse section of broad axis, x 100. C. Transverse section of narrow axis, 

 X 100. D. Transverse section of stolon, x 100. E. Male inflorescence, 

 X 100. The figures were all drawn from the type material of Aneura coni- 

 mitra. 



in loose tufts, and the type-specimens are mixed with another 

 species of Riccardia, too fragmentary for determination. The 

 color varies from a yellowish to a brownish green, becoming darker 

 with age but not blackish. Each thallus is apparently prostrate 

 in the lower part and ascending or suberect above. The prostrate 

 part gives out rhizoids sparingly, usually from very small surface- 

 cells, but the upper portion of the thallus seems to lack rhizoids 

 completely. 



As in the allied species a well-developed axis (Fig. 6, A) shows 

 long-continued growth and a blunt apex, usually attaining a length 

 of 0.5-1 cm. ; its width measures 0.3-0.45 mm. and its thickness 

 nearly 0.2 mm. In some cases the axis itself becomes attenuate at 

 the apex, indicating a cessation of growth, and in this respect 



