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VL The Lithothamnia of the Percy Sladen Trust Evpedition/in H.M.S. Sealark. 
By M. Fosu1e. (Communicated by Mr. J. STANLEY GARD ER, M.A., F.L.S.) 
(Plates 15 & 16.) 
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 algse of the groups of Litho- 
- fhamnionez and Melobesieze. These algæ appear everywhere in suitable localities from 
E 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 
ts further shows us what important part they have also played in former times. But 
knowledge of the different species and of their geographical distribution is as yet 
imperfect, and only the circumstance that during these ten years upwards of 200 
ies have been described shows their great abundance of forms. 
ig the Sealark Expedition Mr. J. Stanley Gardiner collected a rich material of 
these alg 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 alge in the above area, he has given much interesting information *. Below I take 
E permission to quote some of these particulars, with running comments stating the 
. currence of different species in various places. 
‘Of the thirteen species collected and mentioned below, two are new to science, 
3 viz. Lithothamnion gibbosum and Lithophyllum Gardineri. They have been provisionally 
| ibed in * Algologiske Notiser, iii. 
THE CHAGOS ARCHIPELAGO. 
_ The parts explored of this Archipelago, from which Lithothamnia have been brought 
. “ome, are the Salomon and Egmont Atolls. Mr. Stanley Gardiner remarks (2. c. p. 2) :— 
_ “The reefs of the Chagos are in no way peculiar, save in their extraordinary paucity of 
Ay Investigations in the Indian Ocean.—First Report of the Committee, consisting of Sir Joux Murray (Chairman), 
E J. Sraxrgy Garpiner (Secretary), Captain E. W. Creax, Professors We A Henan, 8. d . Hickson, -— 
Td W. Jupp, Mr, J. J. LisrER, and Dr. H. R. Mrr, 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 
pru and Saya de Malha, and also the distribution of Marine Animals.—British Associatim Report, York, 1906. 
SECOND SERIES.— BOTANY, VOL. VII. M 
