Notes and Comment. 75 



pressed with sufficient clearness." Inasmuch as almost every 

 ecological writer has attempted such an expression the subject 

 bids fair to remain in its present state of turbidity until such time 

 as we cease to go into the field with "ideas" which hamper our 

 work. The framing of definitions and the erection of categories 

 and classifications in ecological work has been given too much 

 attention. — -F. S. 



Vegetation of the Kermadec Islands. — Oliver * ahs 

 visited the Kermadec Islands, which lie 1,000 km. to the north- 

 east of New Zealand, and has described their vegetation and 

 flora. A sub-tropical rain-forest predominates, in which the 

 commonest tree is the light-seeded and widely distributed 

 Metrosideros villosa. Only 12 endemic forms are found in the 

 islands, while one-third of the total listed flora of 114 species is 

 made up of pteridophytes of wide Polynesian occurrence. The 

 flora is related most closely to that of New Zealand, less closely 

 to the Australian element present in Norfolk and Lord Howe 

 Islands. — F. S. 



NOTES AND COMMENT. 

 A recent paper by Charles A. Davis on the formation of 

 salt marshes (Economic Geology, Vol. V, No. 7) well illustrates 

 the advantage, and even necessity, of botanical training to the 

 working geologist. vSalt marshes, as defined by the author, 

 are flat areas, often of considerable lateral extent, so situated 

 that they are overflowed at frequent intervals, typically twice 

 dailv at high tide, by salt water. The surface is covered by a 

 growth of a few species of herbaceous plants, of which the domi- 

 nant and characteristic species are grasses, with some sedges 

 and rushes, and, locally, invasions of other types. It has gen- 

 erallv been held that they are formed in shallow water by the 

 upbuilding of the bottom by sediments, until the water is 

 sufticientlv shallow for the common ell grass, Zostera marina, 

 to become established, and by the encroachment of other species 

 which form a tough, peaty accumulation that builds up nearly 

 to the level reached by high tide; but, from a direct study of 

 over a hundred sections in diff"erent marshes and investigations 



♦Oliver, Reginald B , The Vegetation of the Kermadec Islands. Trans. New Zealand 

 Inst., 42: 118-175, 12 pis. 1910. 



