116 . BOTANICAL GAZETTE [FEBRUARY 
as it looks more like the mass of tissue which projects up as a ridge 
into the median groove, the cells being quite too large for those of 
an antheridium. 
Although Hooker considered that the plant should remain in 
the genus Riccia, Corpa placed it in a new genus, Ricciocarpus, 
on the basis of Hooxker’s description and figures which were taken 
from dried material. Corpa’s figures are copies of HOOKER’S. 
BiscHorrF held that there was no real basis for the change, as the 
mature sporophyte does not differ from that of other Riccias, the 
separation being based on the mistaken notion that the capsule 
walls disappear entirely at maturity, and that the genus Riccia 
should not be divided on account of differences in the thallus brought 
about by the different conditions under which the plant grows, since 
the method of fruiting is the same in all the species. 
LEITGEB regarded Ricciocarpus as a distinct genus, on account 
of the more complex structure of the thallus and the grouping of 
the sexual organs. He thought that the antheridia were collected 
into groups similar to those in the Marchantiaceae, but GARBER’S 
results and my own show that LerrcEB was not correct, and that 
the antheridia actually form only one group. The archegonia are 
also arranged in a definite part of the plant in one group. 
The question now arises whether this is a more advanced con- 
dition of development than is found in species of Riccia. In the 
lower species of Riccia, the sexual organs are said to be indiscrimi- 
nately scattered over the surface of the thallus, while in Riccia fluitans 
a regular alternation of single antheridia and archegonia is described.” 
CAMPBELL, in discussing the arrangement of sex organs in Riccia, 
says that in the two forms which he studied, Riccia hirta and Riccia 
glauca, he found as a rule that several of one sort or the other would 
be formed in succession. I have observed the same in Riccia crystal- 
lina, although the older sporophytes appear scattered in the thallus. 
LINDENBERG described the fruit of Riccia crystallina as scattered, 
but the antheridia are described and figured as being in a group 
along the middle part of the thallus. He described and figured 
the fruit in Riccia glauca as being sometimes in rows and sometimes 
scattered. Most of the figures show them in more or less perfect 
rows along the longitudinal axis. 
