Tlie Genus Riccardia in Chile. 137 



can sometimes be distinguished, and sometimes, when the wings 

 are defined with especial clearness, the surface-cells of the branches 

 show distinct trigones. The interior cells are more or less elon- 

 gated and have thickened walls. The primary branches are 

 intermediate in structure between the axis and the secondary 

 branches. 



It should be mentioned that some of the secondary branches 

 and even some of the primary branches toward their tips, instead 

 of being flattened and winged, are subterete and quite wingless. 

 These might be interpreted as stolons, but they are far less differ- 

 entiated than the remarkable stolons found in R. prehensilis and 

 R. Thaxteri. In addition to the photosynthetic branch-systems 

 an axis oi R. calva sometimes gives rise to one or two branches 

 which represents new axes ; these arise in place of photosynthetic 

 systems and soon show the characteristic axial type of branching. 



Sexual branches have not been observed by the writer and male 

 branches are apparently still unknown. According to Schififner 

 the female flower is situated in the axil of a "lobule" and con- 

 tains from ten to twelve archegonia ; Stephani adds that the 

 margin of the female flower is shortly lacinulate ; but neither 

 writer describes the "calyptra" or sporophyte. Schififner's figure 

 shows less regularity than is usually present, but the left-hand 

 side of the thallus represented is fairly typical. 



Some of the important differential characters of R. calva, when 

 compared with R. Savaticri, have already been brought out, espe- 

 cially those relating to size, to the complexity of the photosynthetic 

 branch-systems, and to the differentiation of the sclerotic zone 

 in the axes. The following additional distinctions may now be 

 emphasized : in R. calva the surface-cells do not project, the thallus 

 in consequence does not appear velvety, and the marginal cells of 

 the wings are not differentiated as a hyaline and crenulate border ; 

 in R. Savaticri the surface-cells usually project, the thallus in con- 

 sequence does appear more or less velvety, and the marginal cells 

 of the wings (at least on the ultimate branches) are clearly 

 differentiated as a hyaline and crenulate border. 



7. Riccardia Spegazziniana Massal. 



Riccardia Spegassiniana Massal. Nuovo Gior. Bot. Ital. 17: 254. 

 pi 25, f. 22. 1885. 



