1915-16.] 



233 



beast must perforce dive for its food — cuttle-fish, which live in the 

 depths — the large buoyant head might be efficacious in enabling it 

 to return quickly to the surface. A single Sperm Whale may yield 

 ioo barrels of oil, of which about one-third will be extracted from 

 the head. Besides these four species specimens had been 

 obtained at The Mullet of the Southern Right Whale, Ba/cena 

 australis, and Rudolphi's Rorqual, Balcenoptera borealis. 



The lecture was illustrated by lantern slides and numerous 

 blackboard drawings, and at its conclusion was spoken to by the 

 Chairman and Mr. John M. Dickson. 



"the building of a salt marsh." 



The third meeting of the Winter session was held in the 

 Museum, College Square North, on 18th January. The President, 

 Mr. R. Lloyd Praeger, occupied the chair, and there was a large 

 attendance. The subject for the evening was a lecture by Prof. 

 R. H. Yapp. M.A., entitled " The Building of a Salt Marsh." 

 Prof. Yapp said salt marshes occur in river estuaries and sheltered 

 arms of the sea. They are liable to frequent inundations by sea 

 water, especially during spring tides. The marsh is built up by 

 an accumulation of mud or silt brought down by the river, the 

 mobile silt being bound together and rendered stable by the 

 plants which soon begin to clothe its surface. New silt is 

 deposited by each high tide, and is incorporated with the soil of 

 the marsh by the continuous upward growth of the covering of 

 vegetation. Thus salt marshes, like sand dunes, tend to be 

 gradually built up to higher and higher levels by the frequent 

 addition of fresh mineral particles. In both cases the part played 

 by the living plants is that of binders or stabilisers, Each 

 succeeding stage in this upward extension is overflowed by fewer 

 tides than the preceding one. In consequence each stage is, on 

 the whole, characterised by different species of plants, such as 

 Marsh Samphire, Sea Pink, and various Grasses. Thus in the 

 marshes chiefly dealt with in the lecture, i.e., those of the Dovey 



