308 A. A. HAMILTON. 



sedge, Scirpus cernuus Vahl., which contributes a measure 

 of assistance to the communal effort to secure stability by 

 means of its ramifying stolons. 



At Port Hacking, B. indica was recently noted associated 

 with another mud-creeping member of the same family r 

 Mimulus repens R. Br., the "Creeping Monkey Flower." 

 The former, which had not previously been recorded south 

 of Parramatta, is a common marsh plant in most tropical 

 countries, and, as is the case with many widely distributed 

 species, has acquired an extensive synonomy. The climatic 

 boundaries of these two species overlap in New South 

 Wales from the northern rivers to Port Hacking, M. repens 

 proceeding south from the latter locality to the colder 

 parts of New Zealand, and B. indica extending northwards 

 into warmer latitudes. 



A large area on either side of the drainage channel is in 

 the sole occupation of a maritime sedge, Careoo pumila 

 Thunb., which prefers a position less constantly inundated 

 than that favoured by B. indica, the volume of surface 

 water regulating the boundaries of these two species. The 

 Carex is one of the few plants which are capable of exist- 

 ing on the strand, usually choosing the level stretches at 

 either end of the beach under the lee of the headland, and 

 spreading thence to the dune when the conditions are 

 favourable. It is distributed along the coastal beaches by 

 means of its fruit (utricle), a corky watertight vessel which 

 is produced in large quantities. They are swept off by the 

 high tides which occasionally inundate the colony, and 

 carried by the ocean currents to distant beaches, the 

 buoyant water resistant utricle maintaining the flotation^ 

 and protecting the enclosed seed. A safeguard against 

 tidal invasion is furnished by the subterranean connective 

 arrangement, the tufted leafy members of the colony rising 

 at more or less distant intervals from the stout ropy 



