44 THE ZOOLOGIST. 



They are, however, much shallower. The reason seems fairly 

 clear. The filling agent in the tidal waters is the matter in 

 suspension. In the case of the inland fleets it is the erosion of 

 the surface of the land by rain and weather. The volume of the 

 first must be greater — and, of course, more frequent in its appli- 

 cation — than that of the second. In the case of the inland 

 fleets the settlement will be an even and gradual spreading from 

 the edges to the centre, because there is no current, and they 

 will therefore get shallower without quickly getting narrow. In 

 the case of the tidal creeks there must always be a wash in the 

 centre of the channel, both in the rising and the receding of the 

 tide, which would tend to cut chiefly the centre of the channel, 

 while not preventing its gradual narrowing from the edges. The 

 daily deposit of suspended matter by the tide also accounts for 

 the phenomenon (which I wondered at in my former article) of 

 the level of the salting outside the wall being higher than that 

 of the marsh-land within. If it were necessary to bring actual 

 evidence to prove that the sea once flowed over the marsh, one 

 could point to several beds of cockle-shells in the existing 

 fresh-water fleets, and to the dead shells of periwinkles, and 

 mussels and other bivalves, in soil dug out of the bottom of the 

 ditches. 



Such a district as this, which I have attempted to describe — 

 with its nearness to the wide reaches of the estuaries, with its 

 quiet stretches of inland waters and lagoons, and with their 

 dense growth of reeds and rushes — makes an ideal haunt for 

 members of the Duck family. My notes include observations on 

 eleven species of this family, three of which nest in the district, 

 and five of which, from their late appearances in spring and 

 summer, I am always hoping — perhaps against the dictum of 

 high authorities — to include in my list of nesting birds. A 

 gunner would doubtless add several more to the eleven species 

 that I have noted ; for, whatever may be said against the prac- 

 tice of shooting wild birds, it is the one certain and indisputable 

 method of identifying a species. The quickest observer, with 

 glasses or without, in the hustle caused by a rising mob of 

 startled birds, may be excused for missing the distinctive points 

 of the one or two birds which look different from the rest of the 

 string, and so lose his opportunity of adding a fresh name to his 



