1918] MACCAUGHEY—HAWAIIAN ALGAE 57 
The number of species of the last two groups, excluding dupli- 
cates, was 33 Peridiniales and 31 Bacillariales. The Hawaiian 
waters await an exhaustive study of their plankton; such a study 
will undoubtedly bring to light much new material of great interest. 
Deep water forms 
There have been no large investigations of deep water forms 
in the vicinity of Hawaiian waters comparable to those made in 
other parts of the ocean. The Hawaiian Islands all slope off 
very abruptly into deep water. There is little evidence of shelves 
or platforms. The outer faces of the coral reefs are all very pre- 
cipitous, in striking contrast with the gentle slope of the inner or 
lagoon face. By some geologists the islands have been compared 
to the summits of a row of obelisks. The inter-island channels 
are very deep. The following table will make clear the extensive- 
ness of the deep waters in the immediate vicinity of the islands: 
eeanac between Kauai and Oahu...... 1872 fathoms or 11,232 ft. 
Oahu and Molokai..... 38 o4 “ 
. ‘“¢ Molokai and Maui..... Pee 810 “ 
sy «Maui and Hawaii...... ion0. g192 
Endemism 
The endemism which is so striking a feature of the terrestrial 
flora is exhibited to only a very minor degree by the algae. It is 
difficult to make any very comprehensive statement on this sub- 
ject, as our knowledge of the algal flora of other Pacific Islands is 
still very incomplete. The following are typical forms which may 
be considered endemic in the present status of our knowledge: 
Corallina sandwicensis, Mastophora tenuis, Laurencia nidifica, 
Plocamium sandwicense, Sargassum obtusifolium, S. polyphyllum, 
S. densum, S. incisum, Zygnema spontaneum, Oedogonium globosum, 
Draparnaldia macrocladia, Conferva sandwicensis. Most of the 
algae are either cosmopolitan species or else widely distributed in 
many tropical and subtropical waters. 
COLLEGE or Hawatt 
Honotvutu 
