The Genus Riccardia in Chile. 1 1 1 



d. Thallus roughened throughout the greater part of its extent 

 by rounded papillae, representing projections of surface- 

 cells ; ultimate branches with wings three cells thick 



2. R. prehensilis (p, ii6). 



d. Thallus smooth ; ultimate branches with unistratose wings 



4. R. Thaxteri (p. 126). 

 c. Thallus slightly roughened throughout the greater part of its 

 extent by low papillae, representing projections of surface- 

 cells ; ultimate branches with wings three cells thick 



3. R. Savatieri (p. 124). 



e. Thallus smooth; ultimate branches with unistratose wings 



5. i?. cm/?a (p. 131). 



/. Thallus regularly pinnate, the branches narrower and usually 



shorter than the main axis, the majority being soon limited 



in their growth g. 



f. Thallus irregularly pinnate, the branches usually narrower than 



the main axis but not infrequently showing indefinite 

 growth t i. 



g. Surface-cells of axis more than half the width of the interior 



cells ; ultimate branches flattened and usually with a wing 

 three cells thick 6. R. calva (p. 134). 



g. Surface-cells of axis less than half the width of the interior 

 cells ; ultimate branches often subterete and spine-like, never 

 winged Ji. 



h. Axis covered with a single layer of small cells, a broad median 

 band of narrow cells being differentiated on the ventral 

 surface 7. R. Spegazsiniana (p. 137). 



h. Axis covered with two layers of small cells throughout the 

 greater part of its extent, the ventral surface-cells essen- 

 tially like the others 8. R. spectabilis (p. 140). 



i. Thallus with few or no latent branch-rudiments in the older 

 part y. 



i. Thallus with numerous latent branch-rudiments even in the 

 older part q. 



j. Axis soon becoming ascending or suberect, the plants forming 

 loose tufts ; ultimate branches without unistratose wings k. 



j. Axis prostrate throughout the greater part of its extent, the 

 plants forming depressed mats ; ultimate branches often 

 with unistratose wings two to five cells wide p. 



