54 C. HEDLEY. 



acres in extent. At intervals of weeks or months, the lake 

 is swollen by rain and breaks through the sand dam, the 

 lake is partly drained, the sea enters, the waves restore 

 the barrier and the cycle recurs. Such a sheet of water 

 has an extreme range from salt to fresh and from warm to 

 cool. On a level floor two or three feet deep is a dense 

 monotonous carpet of the slender threads of Buppia mar- 

 itima. The fauna is a scanty one. In Deewhy Lagoon I 

 collected the following mollusca: — Tatea rnfilabris, Pota- 

 mopyrgus ruppice, Salinator fragilis, Modiolaria subtorta 

 and Erycina helmsi. 



Such a lagoon is a favourite resort of waterfowl. The 

 following list of the birds which frequent such a lagoon and 

 adjoining beach was kindly drawn up for this article by 

 Mr. A. J. North : — Pelecanus conspicillatus, Plotus novce- 

 hollandice, Sula serrator, Phalacrocorax carbo, P. melano- 

 leucas, P. sulcirostris, Chenopis atrata, Anas superciliosa, 

 Biziura lobata, Hcemotopus longirostris, Charadrius 

 dominions, Numenius cyanopus, Tringa acuminata, Sterna 

 bergii, Gabianus pacificus, Larus novceliollandice, and 

 Podiceps novcehollandice. Parasitic cycles alternating 

 between sea fowl and marine invertebrates such as have 

 been elaborated in Europe/ will probably be discovered 

 here also. 



THE OCEAN REEF. 



Rocky ground facing the open sea supports the richest 

 flora and fauna. For here the water is most thoroughly 

 aerated by the surf; here is the greatest safety from mud, 

 so inimical to many marine creatures, and here is the first 

 landing place for immigrant spores and larvae, transported 

 by winds and currents from abroad. 



Contrasting with these advantages is the constant danger 

 of being swept away by the waves. The surf that breaks 



1 Lebour, Parasitology, iv, 1911, pp. 416-456. 



