TJie Genus Riccardia in Chile. 115 



vary in length but are mostly one to three cells wide ; along the 

 edge scattered or crowded teeth or cilia with blunt ends are present, 

 each being mostly two to four cells long and one or two cells wide 

 at the base. The cell walls of the lamellae are thickened, especially 

 the bounding walls of the marginal teeth, but trigones are either 

 absent or indistinct. The thallus-wings, which bear no ventral 

 lamellae, are mostly five to seven cells wide and are more or less 

 crispate, the margin being sinuate and also variously crenate, 

 crenulate or denticulate. Trigones, which are sometimes confluent, 

 are usually conspicuous, having convex sides. The bounding 

 walls of the wing-cells are furthermore strongly and uniformly 

 thickened, this feature being especially distinct along the margin. 



The axis gives rise to two types of branches : slightly spreading 

 branches with unlimited growth, which represent new axes and 

 which are only occasionally produced ; and obliquely spreading 

 branches with limited growth, which represent the axes of photo- 

 synthetic branch-systems. Branches of the second type occur 

 abundantly and arise at intervals of 1.5-3 ^i^- o^ each side of the 

 axis. They show a tendency to be subopposite and are mostly 

 5-15 mm. long and 0.6-1 mm. wide. Each branch usually gives off 

 on each side from six to ten crowded secondary branches, spread- 

 ing obliquely and becoming successively shorter toward the apex 

 of the primary branch. The upper secondary branches are simple 

 but the others give off crowded tertiary branches and those toward 

 the base may even show an occasional quaternary branch. The 

 photosynthetic branch-systems formed by these crowded branches 

 of various ranks are approximately ovate in outline and are often 

 so close together that they overlap. The ultimate branches of 

 whatever rank (and the tips of branches which are not ultimate) 

 are mostly 0.3-0.4 mm. wide and are sometimes decurved. The 

 median portion, which is still clearly set off from the wings, is only 

 three cells thick and the rows of ventral lamellae are reduced to 

 two. The wings are essentially like those of the axis, and the 

 wings of a branch are continuous at the base with the wings of the 

 higher axis, the only regular exception being at the base of the 

 primary branches, where the main axis is wingless for a very short 

 distance. Between the main axis and the ultimate branches are all 

 possible intergradations. 



The only specimens of R. fuegiensis seen by the writer are sterile 

 or female. Male branches, however, are figured by both Mas- 



