almost evervwliero in sliellfisli bedded on our ooasts, and 

 its sio'iiificaure lies not so much in its mere presence as in 

 its relative ahuiidaucc. It wil] l)e seen ±'rf)ni the results 

 staled al)()Vf (liat />. roH was very abundant in scveial of 

 the mussels examined: these were t lu'V tliat wei'e 

 eollceled from the piles in the neio-hhourhood of the break 

 in tile pipe. Two nuissels wei'c fpiite sterile, and in ont> 

 or two others the microbe was present in very small 

 tjuantity: these latter shellhsh were collected f'l'om the 

 piles some considerable distance from the break in tlie 

 ])ipe. ( )nly in one or two of the mussels examined was the 

 decree of pollution at all excessive. 



It is probable that the faulty condition of ti)e sewer 

 ])ipe is th(> cause of the ji'ieater |)art of the pollution of the 

 mussels. ihe eddies caused l>y the tide round the piles 

 have excavated a shallow flutter directly beneath the 

 sewer pipe. As the tide lays ])are the sands, this oHittev 

 becomes hlled with a mixture of sea-water and sewage 

 tlowinj:^ from the break in the pipe. Then when the tide 

 beo-ins to flow, some of. this water becomes washed up 

 aj^ainst tlie mussels on the piles, and the former become 

 pollnted. If the sewer pipe were in propei- repair, so that 

 all the discharg-e flowed from its extremity, and still more 

 if there were an interceptinp: tank at the pumpinfj station 

 and the seAvage were only liberated on the ebb tide, I 

 think that the pollution of the mussels would be veiy 

 slight, and would be due only to the slight amount of 

 general pollution of the sea caused by the sewage from 

 the towns at the entrance to the Menai Straits, 



