458 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



"New Gut Channel," instead of through Pinfold 

 Channel, the former entrance to the Ribble. It will be 

 seen that there is a most extensive tract of sandbanks 

 through which relatively narrow, shifting and shallow 

 channels make their way. These channels receive the 

 sewage from a very large population : Preston, about 

 120,000 people; the Southport and Birkdale districts, 

 about 55,000; Lytham, about 10,000; Fairhaven and 

 Ansdell, about 4,000; and St. Anne's-on-the-Sea, about 

 7,000. The Preston sewage is treated by coarse 

 screening, sedimentation and irrigation over about 500 

 acres of land on a sewage farm, and it is not liberated on 

 the ebb until the level of water in the channel has sunk 

 below the level of the training walls, while its liberation 

 on the flood involves an enormous dilution by the 

 inflowing sea water. The outfall is about 6 miles distant 

 from the nearest cockle beds, and the estuary here is 

 about 6 miles in width, and it is about 4 miles distant 

 from the nearest mussel bed. The Southport sewage is 

 treated by septic tanks and continuous bacterial filters. 

 The Birkdale sewage is treated by sedimentation, filtra- 

 tion and irrigation. Both Southport and Birkdale 

 sewage discharge into a brook at Crossens, which con- 

 tinues as a gutter across the sands towards Pinfold 

 Channel. The sewage from Lytham, Ansdell, Fairhaven 

 and St. Anne's is discharged into the channel in the 

 crude condition. 



The shellfish beds in the Eibble estuary are situated 

 on the lower parts of the sandbanks — Horse Bank, which 

 is to the south of the channel, and Salter's Bank, which 

 is mainly to the north. Mussels are not important, and 

 the only beds at present are those at St. Anne's, on the 

 foreshore sloping down to. what used to be the North 

 Channel ; one or two small banks on the foreshore and in 



