92 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
The writer found repeatedly a species of Megaceros closely re- 
sembling the species first described by him from Java* but after- 
wards found abundantly throughout the Malayan region. This 
genus, like Dumortiera, is characteristic of very wet, shady local- 
ities, and its thin-walled, green spores are certainly not fitted to 
being dried up and transported over long distances by the wind. 
The same may be said of the related genus, Dendroceros, which 
inhabits the dripping rain-forest of the higher altitudes. The 
latter was found by the writer only at an elevation of about 4000 
feet, in regions of almost constant rain. 
Other characteristic thallose liverworts of the upper rain- 
forests were species of Pallavicinia, Symphyogyna, and Aneura 
(Riccardia). One of the last-named genus appears to be very 
close to A. maxima Schiffn. of Java. 
It may be safely asserted that there is a marked resemblance 
between the liverwort floras of Hawaii and the Malaysian region, 
but further material is necessary before the exact degree of re- 
lationship can be established. 
The Islands at present consist almost solely of volcanic masses, 
and it is very evident that the volcanic activity has proceeded from 
the northwest to the southeast. 
The oldest formations in the north island, Kauai, and part of 
Oahu, show much weathering and disintegration, while in the 
newest and largest island, Hawaii, volcanic activity is still in 
progress. 
Hillebrand made a careful study of the distribution of the 
vascular plants of the Islands and found that there is a marked 
increase in the number of species, especially endemic species, in 
the older islands, this being specially marked in Kauai, where pre- 
sumably the evolutionary forces have been at work for the longest 
time. 
“Тһе preponderance of the Australasian-Malaysian elements 
in the Hawaiian flora, indicated by a study of the liverworts, is 
amply confirmed by a comparison with the vascular plants. This 
will be sufficiently evident from an examination of the tables 
appended, based upon Hillebrand's Flora of the Hawaiian Islands. 
It is evident at a glance that the Australasian, Polynesifin, and 
* Campbell, D. H. Ann. Bot. 21: 469. 1907. 
