150 THE BIOLOGY OF THE FUNAFUTI ATOLL AND REEF FORMATION. 



with seaweeds, either Lithothamnion or the green species, the presence of which 

 rendered the results somewhat vague, since any gas collected might have arisen from 

 either the coral or the plant. In all cases where the absence of seaweed was assured, 

 as in that of coral placed in boxes, and some pieces growing on the sandy bottom of the 

 lagoon, absolutely no gas was obtained, although the bottles were in position more 

 than two weeks at a time. The only case in which gas was obtained was that of an 

 Astrsean coral which was growing on Lithothamnion* 



(D.) Observations on the temperature of the sea water surrounding an atoll. 

 The following few observations were taken at Onoatoa, in the Gilbert group, by means 

 of a minimum thermometer kindly lent ine by Mr. H. C Russell, F.R.S., during 

 dredging operations about \\ miles off the shore, on November 25th, 1898. 



Temperature of air at the time (10 o'clock a.m.), 86° Fahrenheit. 



Surface water : 81° F. At 60 fathoms, 80° F. 



At 17 fathoms, 81° F. At 90 fathoms, 72^° F. 



The glass tlask in which this gas was collected was unfortunately broken during transit. 



