THE BIOLOGY OF THE FUNAFUTI ATOLL AND REEF FOEiSIATION. 127 



formation of reef rock are seen between the islets of Pava and Mulitefala, where large 

 areas of living Heliopora ccendea and Millepora alcicornis are being slowly smothered 

 by Lithoth amnion and are being transformed by the process above described into the 

 typical rock of the reef platform. 



Traced in an easterly direction, lagoonwards from the islet of Fualopa, and within 

 a short distance of the last shoals, the water sinks into depths which make investiga- 

 tion by means of the water-telescope impossible. Eighteen dredgings, by means of 

 the sand pump, at intervals of half-a-mile across the lagoon (tor positions see Plate 1), 

 showed that the whole of the bottom of the lagoon consists of nearly pnre Halimeda 

 sand, very little besides being brought up by the pump. Foraminiferal sand was met 

 with only in close proximity to the reef platform on either shore of the lagoon. The 

 foraminifera from these dredgings have been already described by Mr. Frederick 

 Chapman.* 



On approaching the eastern rim of the atoll, near the Island of Funafuti, one is 

 greatly struck by its general lifeless aspect as compared with that of the western rim. 

 Shoals close to the platform are absent ; there is no living Heliopora ccendea, just . 

 as there is a total absence of the branching and knobby species of Lithothaninion , 

 although dead fragments of the latter may be picked up on the beach. Of corals 

 only a few species are represented, the Porites limosa (yellow), as well as the purple 

 Porites and PocUlopora paucistellata ^ihe mushroom corals, and the soft corals, but all 

 the true corals occur in small number, and never form the continuous living covering 

 of the western rim. 



The edge of the eastern lagoon platform itself shows very little coral growth, but 

 Halimeda is abundant everywhere. The shoals which are present some distance out 

 exhibit the same method of growth as those of the west. Soft coral, however, which 

 is sparingly represented to the west, is very abundant on these eastern shoals. 



The lichenous Lithothamnion, though present both on the shoals and on the edge 

 of the reef, is A^ery inconspicuous on this side of the lagoon. It does not seem to be 

 of the same vigorous growth, and is dull in colour, so that it may easily be overlooked, 

 and yet the greatest thickness of pure Lithothamnion growth obtained on the atoll 

 was collected from the shoals in this locality. 



The platform is devoid of life with the exception of numerous patches of Halimeda 

 and several clusters of Porites limosa. It reaches up to the sandy beach of the 

 island, the beach overlying it. The island has then to be crossed in order that the 

 eastern ocean platform may be reached. 



There the shore has the same barren aspect as that of the eastern shore of the 

 lagoon. Coral growth is so scanty and the few scattered pieces are, as a rule, so sinall 

 in dimensions that it is possible to walk over considerable distances along the outer 

 portion of the platform without seeing more than half-a-dozen small living coralla of 

 Pocillop)ora grandis. * 



* See ' Linnean Soc. Joi;rnal ' (Zoology), vol. xxviii (1900-0-3), -p. 161. 



