704 MESSES. F. CHAPMAN AND D. MAWSON ON [Nov. I906, 



taining, in more or less abundance, the joints of Halimeda. No. 963 

 (blocks from High Cliff, Flying-Fish Cove) contained Halimeda 

 associated with Litliotliamnion, and Lepidocyclina, together with 

 other foraminifera ; the Lepidocyclina, however, was in a frag- 

 mentary condition, and appeared to be derived. This rock was 

 apparently transitional between the Miocene and the more recent 

 limestone. 



Other samples from Christmas Island containing Halimeda are 

 No. 935 (Halimeda, Litliotliamnion, and foraminifera) ; 215 (large 

 Halimeda, Litliotliamnion, foraminifera and polyzoa) ; 862(Halimeda, 

 Litliotliamnion, foraminifera, corals, nullipores, echinoids) ; 403x1 

 (Halimeda, Litliotliamnion, foraminifera, echinoids) ; 200 (corals, 

 Halimeda, Litliotliamnion, gastropoda, foraminifera) ; 202 (coral- 

 rock with occasional joints of Halimeda and foraminifera) ; 208 

 (coral-rock with Halimeda and foraminifera) ; 209 (Litliotliamnion, 

 Halimeda, foraminifera, corals, echinoids, polyzoa) ; and 1032 

 (Litliotliamnion, Halimeda, foraminifera, corals, echinoids, polyzoa, 

 lameliibranchs). 



The limestone-specimen No. 935 is, from our present standpoint, 

 one of the most interesting of the Christmas-Island rocks yet 

 examined. It occurs on the central plateau at 800 feet above 

 sea-level, in pinnacles projecting from the soil. The rock is a 

 crystalline limestone crowded with Halimeda and Litliotliamnion, 

 and in its general manner of occurrence may be compared with our 

 Halimeda-Liuiestones from the New Hebrides. Of this rock 

 (No. 935) Dr. C. W. Andrews writes as follows l : — 



* It seems to be a shallow-water rock, such as might well accumulate in a 

 lagoon.' 



Funafuti (Ellice Group). 



The enormous quantity of Halimeda accumulating in the neigh- 

 bourhood of many of the so-called ' coral-islands,' whether in the 

 lagoon or in the quieter waters of the outer reef- slope, is forcibly 

 brought home to us by the description of the deposits met with at 

 Funafuti. The results of the two borings in the Funafuti lagoon 

 showed the Halimeda-' sand ' to be at least 80 feet thick in each 

 place 2 ; and shallower parts of the lagoon-floor were found by 

 Messrs. David, Halligan, & Finckh to be covered by a luxuriant 

 growth of the same calcareous seaweed. 3 



Evidence such as this shows that the important deposits of 

 calcareous plant-remains accumulating at the present day, can 

 scarcely be paralleled by any deposit laid down in former geological 

 periods excepting, possibly, the limestones of the Alpine Trias which 

 owe their origin to the thallophytes Diplojiora and Gyroporella. 



1 'A Monograph of Christmas Island ' London, 1900, p. 289. 



2 ' The Atoll of Funafuti ' p. 162. (The depth of the water is deducted from 

 the figures given in the report quoted.) 3 Ibid. p. 151. 



