The Genus Riccardia in Chile. 151 



among the archegonia. The "calyptra" when mature is about 2.5 

 mm. long and 0.8 mm. wide ; the corona is low and hardly distin- 

 guishable except when young, and the surface is roughened by the 

 peeling off of cells. 



The published descriptions of R. alcicornis imply a certain 

 amount of dichotomy in the thallus. According to the original 

 account the plants are bipinnately branched, but it is added that 

 the "rami seu laciniae" are "basi subdichotomi superne subpinnatim 

 divisi." The idea of dichotomy is brought out still more clearly 

 in the Flora Antarctica figure (32, pi. 160, f. 8), while Stephani 

 states definitely that the "truncus" is "repitito furcatus .... f urcis 

 regulariter bipinnatis." He expresses a similar idea in his 

 description of Aneura siibnigra, where he states that the "frons" 

 is "superne furcata, furcis dense regulariterque tripinnatis". 

 Unfortunately the original specimens of Jungermannia alcicornis 

 and Aneura siihnigra, as the accompanying figures will show, fail 

 to support these statements. As already noted, a branch is some- 

 times produced which approaches or even equals the main axis in 

 size and in the complexity of its subdivisions, but branches of this 

 type occasionally occur in most species where the branching is 

 typically pinnate and are not a sufficient reason for designating 

 these species "dichotomous." On the whole it is the pinnate 

 feature in the branching of R. alcicornis which is really distinctive. 



Stephani's description of Aneura subnigra is very brief and 

 brings out no features which would distinguish the species from 

 R. alcicornis. The specimens in fact agree in all essential par- 

 ticulars. His figure of A. subnigra, representing the cross section 

 of a primary branch, is highly diagrammatic and shows an improb- 

 able regularity in the form and arrangement of the cells. The 

 blackish color, which would account for his specific name, is by no 

 means constant. When it occurs it is due to minute bluish black 

 bodies inside the cells, but the nature of these bodies has not been 

 determined. They are of about the same size as the chloroplasts. 

 In the description of Jungermannia alcicornis a blackish coloration 

 is mentioned in connection with old and dry plants, and an occa- 

 sional branch of the type specimen shows brownish or blackish 

 particles in some of the cells. They are less distinct, however, than 

 in the specimens of A. subnigra, owing perhaps to the much 

 greater age of the material. 



