114 CALIFORNIA ACADEMY OF SCIENCES [Paoc. 4th Ser. 



and by its dioicous inflorescence and smooth calyptra, the 

 last two characters being quoted from other writers. In 1900 

 Schiffner 11 discussed "Aneura pinnatifida Nees" at length and 

 showed that the species was an aggregate, based partly on 

 tropical material and partly on European material. The trop- 

 ical material, in his opinion, represented a species closely re- 

 lated to R. multiUda (L.) S. F. Gray, while the European 

 material agreed in great part with Riccardia sinuata (Dicks.) 

 Trevis., a species antedating Nees von Esenbeck's species by 

 a number of years. Schiffner therefore recommended that 

 Aneura pinnatifida should no longer be recognized as a species 

 and that the European specimens of the so-called A. pinna- 

 tifida should be definitely referred to R. sinuata. He showed 

 further that the inflorescence of R. sinuata was autoicous (in- 

 stead of being dioicous) and that the calyptra was covered 

 over with inflated or tubular surface-cells (instead of being 

 smooth), thus agreeing in these respects with R. major as 

 described by Howe. 



In connection with R. sinuata Schiffner discussed R. major 

 and reached the conclusion that the two species were very 

 close allies. At the same time he pointed out certain slight 

 distinctions between them and suggested that they be recog- 

 nized as distinct species, at least provisionally. His differen- 

 tial characters were drawn in part from the sporophyte and in 

 part from the gametophyte. Six years later he 12 showed that 

 the sporophytic differences were less constant than he had sup- 

 posed but still insisted on the importance of the gametophytic 

 differences and continued to regard R. major as a valid species. 

 According to his account R. sinuata is a true aquatic; the 

 thallus is rigid, fleshy and brittle and shows a bipinnate or 

 tripinnate branching; the main axis is six to 10 cells thick, 

 and the most delicate branches are never fewer than four or 

 five cells thick ; while the axis and leading branches broaden 

 out at the apex. R. major, on the other hand, is a swamp 

 plant rather than a true aquatic ; the thallus is thinner and less 

 rigid than in R. sinuata and shows a simply pinnate or rarely 

 bipinnate branching; the main axis is only five cells thick 

 on the more robust specimens, and the branches are only three 



"Lotos 48: 357-382. 1900. 



"Oesterr. Bot. Zeits«hr. 56: 170. 1906. 



