452 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



east of the pier the shore is rather rocky and rises' steeply. 

 This, however, is a matter for an engineer's opinion, and, 

 obviously, the main question to be considered is that of 

 cost. Would it be worth while to construct expensive 

 works considering the restricted mussel fishery in the 

 estuary? This is not all, however; even at Penhelyg 

 Point the sewer outfall is only one half-mile away, and 

 it is possible that, with a possibly unregulated (or 

 imperfectly regulated) discharge of sewage, some of the 

 latter might reach the tanks. This is a danger which 

 could, perhaps, be anticipated and guarded against by a 

 thorough survey of the estuary with regard to the 

 direction of flow of water at all states of the tide, and in 

 all conditions of weather. 



3) The Mussel Beds at Barmouth. (Plate III.) 



The estuary of the Mawddach river, like that of the 

 Dovey, is a very considerable expanse of water near the 

 height of the tide. It varies in width from about half 

 a mile to more than a mile. But at low water the 

 channel contracts to a strip of about two or three hundred 

 feet in width, and the greatest depth in it is only about 

 5 fathoms at low water of spring tides, while here and 

 there the depth is very much less. The depth on the bar 

 is only about \ to \ fathom, so that very much the 

 same conditions that we have noted in the case of Port 

 Madoc estuary may also exist here : during low neap 

 tides the flushing out of the estuary from the sea may 

 not be complete. Yet it is the case here (but not at 

 Port Madoc) that the mouth of the estuary is a ' bottle- 

 neck ' ; for there is a very -considerable basin east from 

 Barmouth which is filled at every tide, and the flow 

 through the bottle-neck may be more effective in scouring 

 th=e channel than one, at first, might expect. 



