156 THE ZOOLOGIST. 



The absence of rocks and seaweeds forbids the abundance 

 of certain fishes and Mollusca, so that the ornithologist may 

 in some measure infer as to what particular species of birds 

 would from choice be usually scarce or abundant. Surface- 

 feeders are well represented, but those which dive or prey 

 upon Mollusca, and those that delight in rocky and pre- 

 cipitous habitats, are generally uncommon, or merely storm- 

 driven stragglers. An exception exists in the Scoter, numbers 

 of which frequent the Broads all the winter, feeding upon the 

 smaller bivalves which are apparently in spots plentiful at the 

 bottom (vide note on Scoter). 



The northern sand-hills mostly slope gradually into marshy 

 levels or cultivated fields, reaching their level in the Broad-lands 

 and the valley of the Bure. 



Southwards of the town, after passing the mouth of the 

 Yare, stretching away towards Lowestoft, is a range of crumbling 

 sand-cliffs, the fields above which are cultivated to the very edge. 

 A straggling colony of Sand -Martins nests here. All westward of 

 the cliffs is cultivated, and merges off into a fairly well-wooded 

 district, notably at Fritton and Belton, excepting which scarcely 

 anything worthy of that name exists within the limits comprised 

 in the district to which these remarks refer. Small thickets 

 occur at the margins of some of the Broads, and a few carrs of 

 alder and willow, interspersed with birch, are irregularly scattered 

 over the swampy parts of the marshes, but seldom covering more 

 than an acre or two of ground. 



To the west of the town is the great alluvial flat, once the bed 

 of the great estuary known to the Romans as Garienis ostium, and 

 up which their galleys passed to their camp at Caistor, beyond 

 Norwich. Remains of this estuary and the branches now exist 

 in the famous Norfolk Broads, most noticeable of which is 

 Breydon Water, into which the Yare, the Waveney, and the Bure 

 empty their sluggish streams. 



Before Breydon was walled* and the rivers banked, and the 



* Breydon, five miles long and one in width, is surrounded by a winding 

 mound or dyke, faced with jagged flints and backed with grass, forming a 

 triangular barrier. The rivers are similarly confined. The ditches formed 

 by the soil removed drain the marshes, and are connected with a network of 

 others. Steam drainage mills pour the surplus water over into the rivers. 

 Hence, although the marshes grow drier year by year, they are always below 

 the level of high water. 



