170° BOTANICAL GAZETTE [MARCH 
indication of elaters or sporophyte foot of any kind. Thus, as 
in Riccia, Ricciocarpus presents the simplest of hepatic sporo- 
phytes, which fact, I think, should be associated with a strictly | 
aquatic habitat. To my knowledge, all floating liverworts have 
this simple form of sporophyte, while nearly all of those normally 
living and fruiting on the soil (including the submerged Riella) 
have to some degree developed sterile structures in addition to 
the simple capsule wall, The soil contact rationally appears to 
be a necessary stimulus to any extensive sterilization of sporoge- 
nous tissue in the progressive manner contemplated by Bower 
(15), because only on the soil does it seem possible so to estab- 
lish an independent sporophyte. 
A summary of the fruiting period about Chicago in 1902 is 
approximately as follows: 
April 10-20. Formation and development of antheridia. 
April 20— May‘. Formation and development of archegonia. 
April 25—-May 5. Fertilization. : 
April 25 June 20. Growth of sporophyte, production and shedding of 
spores. 
Any given sporophyte matures in about three weeks from the 
time of fertilization, and when mature exceeds the volume of the 
egg from which it is derived about five hundred times. In the 
structure of its thallus Ricciocarpus is much more complicated 
than any Riccia. But the most important points in classification 
are connected with the arrangement of the sex organs on the 
thallus and the structure of the sporophyte. In the lowest 
species of Riccia the sex organs are scattered indiscriminately 
over the surface, while in Riccia fluitans there is said to be a 2; 08 
lar alternation of single antheridia and archegonia. Leitgeb 
based his classification of the plant on old, isolated, exceptional 
groups of antheridia. The antheridia should be considered as 
being produced in a definite region of the plant in one large 
group, which is followed by the production of a similar group of 
archegonia. These groups may be compared to the arrangement 
found in Asterella, Sauteria, etc., and mark the farthest advance 
made by Ricciocarpus. On the basis of its complicated thallus 
and definitely limited regions of sex organs, I should place Ric- 
