198 BOTANICAL GAZETTE [SEPTEMBER 
GOEBEL (’98, p. 240) points out the similarity in the development 
of the antheridium of Monoclea to that of the Marchantiaceae, which 
was figured (but apparently not recognized) by RucE (’93), but still 
GOEBEL does not definitely include Monoclea in that family. 
CAMPBELL (’98) for the first time placed Monoclea definitely in 
the Marchantiaceae, because of the form of the thallus and the pres- 
ence of two types of rhizoids, but especially because of the structure 
of the male receptacle and of the antheridium and archegonium. 
Practically all the evidence collected in the present research seems 
to the writer to favor the view of CampBeEtt. For it is found that the 
thallus of Monoclea is like that of the Marchantiaceae in gross struc 
ture, in the mode of growth and branching, in the type of initial cell, 
and as I have been able to show in the possession of tuberculate rhiz- 
oids as well as thin-walled ones, in which latter character Monoclea 
differs from all described Jungermanniaceae. 
These tuberculate rhizoids have been overlooked by earlier 
observers probably because of their comparative rarity, and because 
of the very few tubercles present in each rhizoid (jigs. 23, 24). The 
tuberculate rhizoids are ro to 15 in diameter, while the other rhizoi 
are 25 to'35 in diameter and much thinner walled. The distribu: 
tion of these two types of rhizoids is perfectly constant, as was shown 
by Lerrces (’77, p. 63). The thick-walled ones are scattered more 
generally over the thallus, and always lie nearly parallel to it, while 
the thin-walled ones are clearly grouped near the mid-line of the thallus 
and stand_out perpendicularly to it (figs. 8, 9, 28). This is just the 
relative’position of these two types of rhizoids in, for example, March- 
antia or Fegatella (CAVERS ’04, jig. 17), where the tuberculate rhizoids 
arise under the ventral scales along the whole costa and run back ; 
between these scales to the base of the thallus, while the large, thin- 
walled ones arise in groups and stand straight out from the thallus. 
The tuberculate rhizoids of Monoclea are always thin-walled a 
the distal end, which probably means that there is a long-continus’ 
growth in length in this region. Some of them surely reach a very 
great length. 
The absence of the ventral scales characteristic of the rt 
Marchantiaceae, and of the air chambers with their chlorophy 
bearing cells, is probably, as CAMPBELL has suggested, to be 
