“226 BOTANICAL GAZETTE [SEPTEMBER 
Hawaiian Islands.2, He says: ‘No indication of lacunae can be seen 
either near the apex or farther back, the whole thallus being composed 
of a perfectly continuous tissue without any intercellular spaces.” 
Schiffner? describes two species of Dumortiera from Java, D. ¢richo- 
cephala and D. velutina. Of the first he says: ‘‘Frons oberseits ohne 
oder nur mit zerstreuten Papillen iibersat.” In neither species does 
he mention the presence of any trace of air chambers or reticulations. 
In the possession of numerous papillae on the upper surface D. 
velutina shows itself to be less reduced than D. ¢richocephala. 
Z. Kamerling* gives a figure of D. hirsuta which shows the upper 
surface thickly covered with unicellular papillae. He refers to Leitgeb’s 
work on DP. irrigua, but does not mention finding any trace of chambers 
in D. hirsuta. My own observations on the last-mentioned species, 
which grows rather abundantly in two situations around Chapel Hill, 
bring out the presence in some cases of air chambers in the young 
parts of the thallus, which closely resemble those in D. irrigua. 
Our species, like others of the genus, grows in wet, springy places 
where the water is constantly trickling through, and it evidently requires 
more moisture than any other members of the Marchantiaceae (with 
the exception of Riccia) that occur in this region. Z. Kamerling,’ in 
his classification of the Marchantiaceae according to biological types, 
has considered Dumortiera with good reason as typically hygrophilous, 
and there seems little doubt that the loss of its air chambers is due to 
its semi-aquatic life. 
The spot where Dumortiera is most abundant here is a gentle 
rocky slope on the north side of a well-wooded hill, where spring water 
is constantly oozing out and keeping the thalli saturated. Plants from 
this place show no air chambers. The other spot where Dumortiera 
has been found is under a series of overhanging rocks that have been 
hollowed out so as to form caves 8 to 12% deep. At the base of 
these caves the liverwort grows on the damp porous sand, where the 
water never seems to accumulate so as to cover the plants. Specimens 
from this situation can be plainly seen with the naked eye to be retic- 
ulated over the entire surface, as shown in fg. z, which is from 4 
See also CAMPBELL, The systematic position of the genus Monoclea. Bor. GAZ. 
25: 272-274. 1898. 
3 Die Hepaticae der Flora von Buitenzorg. Leiden. 1900. 
" , Zur Biologie und Physiologie von Marchanticeen. Pp. 73, p45. 4- Miinchen, 
1897. 
5 Op. cit. p. 38. 
