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No. X.—THE LITHOTHAMNIA. 
By M. Fostiz. 
(Communicated by Mr. J. Stantey Garpiner, M.A., F.L.S.) 
(Plates 19 & 20.) 
Read 20th June, 1907. 
Great areas of the Indian Ocean, and of other oceans as well, are still unexplored or 
but little known as regards the occurrence of calcareous algze of the groups of Litho- 
thamnionez and Melobesiez. These algee appear everywhere in suitable localities from 
Spitzbergen and Ellesmere Land in the north to South Victoria Land and Louis Philip 
Land in the south. They are known to occur in enormous quantities in many places, in 
the arctic and temperate zones often forming large banks, and in the tropics essentially 
contributing to the formation of reefs. Their occurrence in masses in fossil and subfossil 
layers further shows us what important part they have also played in former times. But 
our knowledge of the different species and of their geographical distribution is as yet 
rather imperfect, and only the circumstance that during these ten years upwards of 200 
new species have been described shows their great abundance of forms. 
During the Sealark Expedition Mr. J. Stanley Gardiner collected a rich material of 
these alge in an area of the Indian Ocean from which they were hitherto almost 
unknown. This material he has kindly left me to determine. As to the occurrence of 
the algz in the above area, he has given much interesting information*. Below I take 
permission to quote some of these particulars, with running comments stating the 
occurrence of different species in various places. 
Of the thirteen species collected and mentioned below, two are new to science, 
viz. Lithothamnion gibbosum and Lithophyllum Gardineri. They have been provisionally 
described in ‘ Algologiske Notiser,’ ii. 
THE CHAaGcos ARCHIPELAGO. 
The parts explored of this Archipelago, from which Lithothamnia have been brought 
home, are the Salomon and Egmont Atolls. Mr. Stanley Gardiner remarks (J. ¢. p. 2):— 
“The reefs of the Chagos are in no way peculiar, save in their extraordinary paucity of 
* Tnvestigations in the Indian Ocean.—First Report of the Committee, consisting of Sir Jonny Murray (Chairman), 
Mr. J. Sranzey Garpiver (Secretary), Captain E. W. Creax, Professors W. A. Herpman, S. J. Hicxson, and 
J. W. Jupp, Mr. J. J. Lisrer, and Dr. H. R. Mixt, appointed to carry on an Expedition to investigate the Indian 
Ocean between India and Africa, in view of a possible land-connection, to examine the deep submerged banks, the 
Nazareth and Saya de Malha, and also the distribution of Marine Animals.—Britisk Association Report, York, 1906. 
SECOND SERIES.—ZOOLOGY, VoL. xu. =[ 93 ] 26 
