332 Campbell—Studies on some East Indian Hepaticae. 
D. calcicola sometimes produces androgynous receptacles like those 
found in D. trichocephala. 
The branching of the sterile plants of D. calcicola is prevailingly 
dichotomous; but in the fertile plants adventitious branches are sometimes 
very freely developed in addition to those which bear the receptacles 
(PI. VIII, Fig. 2). 
A section through the apex of the sterile shoot (PI. VIII, Fig. 4) shows 
very clearly the formation of imperfect air-chambers; but, as in other 
species of Dumortiera , these are open above, and no proper stomata are 
developed. In the older portions of the thallus the air-chambers consist of 
large shallow depressions whose bounding walls form a faint irregular 
areolation on the surface of the thallus (PI. VIII, Fig. 3). 
Text-fig. 9. a. Ventral scale, b. Three rhizoids from the thallus of D. calcicola. x 285. 
The short green cell-rows which are so conspicuous on the floor of the 
air-chambers of Marchantia and Fegatella , for example, in D. calcicola are 
reduced to rounded papillate cells scattered over the surface of the thallus. 
These cells are more abundant than in D. trichocephala. Like the latter 
species there are stiff hairs on the margin of the thallus as well as fringing 
the receptacles, but these hairs are less numerous than in D. trichocephala. 
A section of the older thallus (PI. VIII, Fig. 5) shows a pretty well 
marked superficial layer of small cells, above and below, between which are 
very much larger cells. In the thinner part of the thallus the latter may 
be reduced to a single layer. As in all species of Dumortiera , the ventral 
scales are much reduced, and can only be recognized near the apex of the 
shoot. They are narrow spatulate structures, some of the marginal cells 
forming pear-shaped glands (Text-fig. 9, A, m). 
