ee ain, 
JOHNSON—MONOCLEA 189 
that the work of the latter (though RucE apparently failed to appre- 
ciate this) materially adds to the likenesses between Monoclea and 
the Marchantiaceae, which LEITGEB (’81) had already noted. 
From the presence of two types of rhizoids, the development of 
the male receptacle and the antheridium, and from the structure of the 
mature archegonium made out by CAMPBELL himself, he concludes 
that Monoclea is to be included in the Marchantiaceae. The absence 
of ventral scales and of the air chambers, characteristic of the Mar- 
chantiaceae, he thinks cannot be considered a greater objection here 
than in the case of Dumortiera, in certain species of which he has 
shown that the air chambers are not present at any stage of develop- 
ment. 
THE MALE RECEPTACLE. 
The male receptacle of Monoclea is a slightly elevated oval area, 
4-10"™ long and 2~-3™™ broad, on the median line of the upper sur- 
face of the thallus (fig. r). In general appearance it is something 
like the male receptacle of Fegatella, but in origin it resembles more 
closely that of Fimbriaria (CAMPBELL ’95), since the receptacle is not 
sunken into the thallus and is not the product of several growing 
points, both of which features CAVERS (’04) has shown to be character- 
istic of Fegatella. 
The antheridia of Monoclea occur in groups of fifteen to fifty, 
arranged in four to six rather indefinite longitudinal rows along 
the receptacle (jigs. 1, 2, 4,6). They arise in acropetal succession, 
and the antheridia of the same receptacle may range in development 
from those of a few cells each at the anterior end to nearly ripe anthe- 
ridia at the posterior end (figs. 8, 9). 
The male receptacle arises by the upward growth of the cells of 
the thallus round about and among the antheridia of a group (jigs. 6, 
9). This upward growth of the sterile cells is subsequent to the 
formation of the antheridium rudiments (fig. 6), and thus progresses, 
Be the development of the latter, from behind toward the growing 
point. ; When the formation of antheridia ceases for a time, the grow- 
ing point which has given rise to the antheridia pushes on, forming 
PR of vegetative thallus of normal thickness (fig. g). Thus 
a has an abrupt ending in front, with an elevated and 
i Y overhanging margin, like that on the lateral and posterior 
Bes (jigs. 2, 3, 8 9). 
