Tlie Genus Riccardia in CJiile. i75 



cells on the outside of the axis and a consequent contrast in size 

 when these cells are compared with the larger cells of the interior. 

 In R. Spegazsiniana there is only one layer of small cells, and the 

 contrast in size is very striking; in R. spectabilis there are two or 

 three layers in the median portion of the axis, these cells are all 

 persistent, and the contrast in size is less marked ; in R. Negeri 

 there is only one layer of small cells except for a broad median 

 band on the lower surface, where there is a second short-lived layer 

 on the outside, while the contrast in size is striking toward the 

 margins but less so in the median portion. Both R. Spegazsiniana 

 and R. spectabilis are further distinguished by a regular pinnate 

 branching, in which all (or nearly all) of the branches are limited 

 in growth and clearly different from the axis, and by a complete 

 lack of latent branch-rudiments in the older part of the thallus. In 

 R. Negeri the branches vary in length but are otherwise essentially 

 like the axis, and latent liranch-rudiments are frequent. 



19. Riccardia mycophora sp. nov. 



Growing in thin depressed mats, pale brown (when dry) varying 

 to dark brown : thallus apparently prostrate throughout, the axis 

 strongly flattened but rounded on the edges and wholly destitute 

 of wings, rather copiously branched ; branches narrower than the 

 axis but otherwise scarcely differentiated, often sparingly sub- 

 divided, the secondary branches rarely remaining in a rudimentary 

 condition, usually similar to the primary branches and sometimes 

 giving rise to one or two very short tertiary branches ; axis and 

 branches with a ventral median band of narrow cells containing 

 fungus hyphae : remaining parts unknown. 



Specimens examined: Mayne Harbor, Patagonia, 1888, 

 Voyage of the "Albatross" (U. S., Y., listed by the writer as 

 Aneura uiultifida (?), 8, p. 141). Known only from the type 

 locality. 



The type material of R. mycophora is unfortunately sterile, but 

 the thallus presents certain features which distinguish it clearly 

 from R. Negeri, the species to which it is apparently most closely 

 allied. The plants are pale to dark brown in color and grow in 

 loose tufts in admixture with a second species of Riccardia too 

 incomplete for determination. They seem to be prostrate in habit, 

 but no stolons are present and rhizoids are very sparingly produced. 

 The texture is fairly firm. 



