LITHOTHAMNIA. 



463 



coast of Norway. The banks in these positions are built up entirely of the algae in question, 

 and as a rule each bank comprises only one species, but at the same time it serves as 

 a shelter for a very great number of various animals, though not corals. In such banks is 

 often to be seen an interesting struggle for existence between plants and animals. Further 

 it may be remarked, that in several places along the Norwegian coast rather large quantities 

 of dead Lithothamnia have been brought up by excavators in harbours, where living specimens 

 are no more to be found. On the west coast of Ireland I have also seen great masses of 

 partly dead, partly living, specimens. On the whole, smaller or larger banks appear almost 

 everywhere at least in northern waters, in places where the nature of the bottom allows 

 their existence and the tides are running rapidly. 



In regard to the habitat of the Lithothamnia in the Maldives, Mr Stanley Gardiner 

 kindly communicated to me some observations on the collection, of which I may quote the 

 following. The names within parentheses are added by me as the supposed species in question. 



" The finely branching species or specimens are all from the sand-flat (Goniolithon 

 frutescens). Massive (not branching) forms are practically invariably from the outer, i.e. seaward 

 face of the reef near the breakers. Specimens roughly resembling {Lithothamnion fruticulosum 

 f. crassiuscula and Lithophylluni Kaiserii ?) are almost invariably dredged either to seaward 

 of the reef or in passages generally down to about 25 fathoms. Rounded nodules like 

 marbles or eggs {Lithophyllum Reinboldi ?) are invariably from deep passages into the lagoons 

 of atolls or interiors of banks. They lie there together with similarly shaped masses of 

 Polytrema and Polyzoa (each usually with a nucleus of dead coral). Presumably all these 

 are rolled over and over with the currents. 



" In the lagoons of Suvadiva, Addu and other closed atolls Lithothamnia were never 

 dredged. Perhaps this was partially owing to the sandy or muddy bottom preventing their 

 growth, but even close round shoals, where the bottom was covered with coral fragments, 

 Lithothamnia were never found. In similar situations to the last in the open banks of 

 Miladumadulu and N. Mahlos I have found small growths a square centimetre or so, but 

 never obtained a separate large plant." 



" In reference to the reefs, branching growths (Goniolitlion frutescens) may be found more 

 or less imbedded in the sand of the sand-flat in any situation where they are never uncovered 

 and the water circulates freely. Thus to the E. of Hulule such growths were found, but 

 not on the west or lagoon side. On the reef to the E. (seaward reef) the Lithothamnia pre- 

 sented their usual abundance, most plants being encrusting with smooth surface (Lithophyllum 

 oncodes and Goniolithon Fosliei), some however coarsely mamillated {Lithophyllum craspedium). 

 At the extreme edge under the breakers massive or incrusting growths covered the greater 

 part of the rock on many reefs, and on the reef-flats behind a few plants were growing 

 in hollows. On the W. reef (lagoon reef) of Hulule island no Lithothamnia were ever found 

 except at the extreme edge. Here such growths as existed were very small and crowded 

 out by corals. Several series of dredgings were taken off this reef in 10, 15, 20, 25 and 

 28 fathoms. The only Lithothamnia obtained were two small nodules between 25 and 30 

 fathoms almost off the end of the passage." 



